user16626: I play numerous online chess games and in this question I am self-centred: I play for two purposes: 

to win the game, or when winning is unlikely, to draw the game.
to improve my chess skills, which eventually enables me to win/draw more games.

I do not care about my opponents' fun. I do not care if they feel frustrated or bored. However, I will remain polite and I am against bad sportsmanship.
Here is my logic: when my opponent finds a game non-interesting, they will more likely make inferior or aimless moves, or even blunders, and thus increase my chance of winning.
A few thoughts:

When the opponent invites me into a sharp line, decline it. Make moves to solidify my position instead. Decline most gambits.
Choose boring openings whenever possible.
Choose openings that my opponent does not like, if I know their preferences.

Is the idea of destroying your opponent's fun good? Are there any other strategies to bore my opponent so that hopefully they will lose their patience and start making inferior/aimless moves?

user19192: Something tangible - all things equal, if a piece is pinned or trapped, delaying the capture as long as possible can be a very small psychological advantage.

user224: There are a lot of issues raised here and I'm going to take them in a different order than presented:

Is the idea of destroying your opponent's fun good?

Not in my opinion. From the perspective of winning the game, you seem to believe that denying them fun will lead your opponent to blunder. It may against some players. However, "battle-hardened veterans" will have seen players who use strategies like this and are likely to just play on with no ill effect. For some folks it is the winning that is fun. So if they beat you it doesn't matter what you did during the game; the only way to deny them their fun is to defeat them. Other people have fun just playing, so there may not be an approach you can take that will deny their fun. Thus I don't think this is a dependable method for winning.
Additionally, I will relate a story from my childhood. While I learned the game from friends at school, after a while I could no longer play there. As my family lived "out in the middle of nowhere", I had no one else to play (this was long before ubiquitous internet access) except two step siblings. They were the sort who couldn't enjoy a competition if they didn't win, but I quickly advanced past their skill level and defeated them every time we played. Thus I quickly found myself with no opponents. Unfortunately, this lasted for several years. So, making the game a miserable experience for your opponents could lead to having no one else to play. Of course, if you are better than they are and they are the sort who only enjoys winning, there may not be much you can do, except to teach them to be a better player if they are amenable to that.

I play for two purposes:
1.to win the game, or when winning is unlikely, to draw the game.
2. to improve my chess skills, which eventually enables me to win/draw more games.

Others have already pointed out that the second point is at odds with your proposed strategy of boring your opponents into blunders - you aren't improving your chess skills by taking advantage of opponents' blunders. Also, relying on mistakes by your opponents won't lead you to wins all the time, as you will encounter games in which the other player doesn't make (game changing) mistakes.
As for the actual title question about minimizing your opponent's fun ...
I realize you are primarily discussing on line play. I think that boring your opponent or making them unhappy in the game is harder when you don't even see your opponent, especially if it is someone with whom you are unfamiliar. If it's someone you have familiarity with, then you may be able to play openings they don't like or that are boring and avoid sharp lines. Furthermore, none of these are inherently wrong or necessarily going to induce boredom or displeasure. If you need a draw to win a prize, they are even quite understandable. What I really want to address under this topic is over the board play, where methods of denying can fun include:

Sighing, cursing under your breath, and making other noises when you discover a mistake
Similarly, saying "A-ha!", "Eureka!", "Gotcha!", etc. when something goes your way.
"Smashing" the clock, especially if it is your opponent's and you do it particularly forcefully, making them think you might break it.
Making your move and hitting the clock so fast that your opponent hasn't even had a chance to hit the clock themselves.
Asking to see your opponent's notation sheet because you messed yours up. Double the annoyance if you do it on their turn/time on clock.
Making all your physical movements as if you only have seconds on the clock, even if it is very early in the game or after thinking for quite a while.

As noted in comments, these actions could cause your opponent to register a complaint for distracting behavior that would lead to penalties.

user2655: I'll leave the technical details to people who have played more chess more recently than I have, but I respectfully submit that your intent is counterproductive to your stated goal of 

to improve my chess skills, which eventually enables me to win/draw
  more games.

With chess, as with any competitive game, sport or skill, at the higher levels the best way to improve is to challenge yourself against as many different opponents as possible.
If word gets around -- as it will -- that playing against you is slightly less interesting and engaging than watching paint dry while listening to Mr. Roboto read Galt's speech from Atlas Shrugged, people will start declining to play against you. 
Worst case, you might wind up winning a tournament only to be politely but firmly disinvited from coming back next year.
On the other hand, if they find that playing with you is an interesting challenge, then win or lose they'll gladly do it again next year, and you'll be able to find out what they learned in the meantime. I personally would think that benefit is worth the low, low price of not being a tedious jerk just to win by default.

user13433: I recommend reading Jonathan Rowson's excellent Chess for Zebras, which analyses chess psychology in quite some detail.
One core observation is that humans do inevitably think in stories to make sense of the world around them, and chess is no exception to that. It's actually not easy for the human brain to take a fresh look at each new position (after each move) while completely discarding everything that happened before. 
To some extent, the chess community shares common stories ("folk stories") that will shape the expectations about the ongoing game. For example, the Sicilian defense is linked with the idea of counterattacking and a bloody battle, and many players precisely pick it up because of that reputation. Many of these then don't like to play against the "Anti-Sicilians" not because they would be more threatening than the Open variations, but simply because they lead the story in a completely different ("boring") direction that is less fun to them. By picking such a variation, you may not play the objectively best line, but you can certainly irritate your opponent. Conversely, defenses like the Caro-Kann or Scandinavian are typically picked by players who want a quieter game and won't like if you play more aggressive lines, the French is associated with locked pawn chains, and so on. Of course, it's not wise to go as far as to knowingly play completely unsound lines though. Some less fun for your opponent usually won't make up for hard material (then again, many gambits bank on that in addition to their "objective" compensation).
The book also discusses the question of whether Black "equalizing" should actually be considered as "=" or "=+". The reasoning for the latter is that while the position will still be a draw with perfect play, it's now more "fun" for Black (who "succeeded" in the first-move advantage story that tells him that he has to fight for equality)  than for White (who "failed" in the story that he has to push for the win) and this alone will slightly increase Black's winning chances by the same logic as asked in the question (White will be a bit more likely to "overdraw" and thus make mistakes).

user11629: Most definitely (as in any sport) it is a good idea to play to your strenghts and to your opponent's weaknesses.
This requires:

that you have the time, data and ability to analyze your opponent's games
the ability to be able to play all kinds of styles.

Both of these are just about impossible for beginners though. But as you advance you should  consider this as an additional option. Mastering this is reserved to some of the best players and even among those, many players do have a certain style.
I would not go so far as to chose boring openings consistently. What if your opponent likes boring games as well? Being flexible is a good idea in chess.

user12873: Chess is a zero sum game, so your opponent's disadvantage is your advantage. Therefore, if you are serious and can find any (sportsmanlike) way to make them dislike the game, you should clearly take it. 
Your first two points (declining sharp lines and choosing boring openings) are fine, as long as you won't be more bored than your opponent is. If you prefer positional systems then this will work well, but keep in mind that your opponent has a similar mindset. They will try to get you into sharp lines that you dislike. The struggle here is to see who gets their way, and often the choice of opening and be helpful in dictating the play.
The third point should absolutely be followed, if you're capable of playing different openings. In preparation for world championship matches, the contenders spend months going through their opponent's games, looking for weaknesses. If they find that one opening is particularly difficult, they will choose it.
To be clear though, you should mainly be focused on making objectively sound moves. If there is an opportunity to minimize your opponent's fun, with little to no cost for you, then take it. But don't go into a bad system just because you know your opponent won't like the arising positions.

user4418: 
I play for two purposes: 

to win the game, or when winning is unlikely, to draw the game.
to improve my chess skills, which eventually enables me to win/draw more games.


These are good goals, although you might want to add "to have fun" because if you don't have fun you are quickly going to lose motivation.

I do not care about my opponents' fun.

Also good, because if you care too much about your opponents' fun you will end up losing focus and not follow your two stated primary goals.

Is the idea of destroying your opponent's fun good?

No, it is counterproductive. If you start focusing on how much fun your opponent may or may not be having then this can only distract you and detract from your game. If, for the purposes of this question you are going to be truly self-centered then you cannot let your opponents' feelings, good or bad, enter into your considerations. It can only lead to bad play on your behalf. Concentrate on making the best moves.

16626: <p>I play numerous online chess games and in this question I am self-centred: I play for two purposes: </p>

<ol>
<li>to win the game, or when winning is unlikely, to draw the game.</li>
<li>to improve my chess skills, which eventually enables me to win/draw more games.</li>
</ol>

<p>I do not care about my opponents' fun. I do not care if they feel frustrated or bored. However, I will remain polite and I am against bad sportsmanship.</p>

<p>Here is my logic: when my opponent finds a game non-interesting, they will more likely make inferior or aimless moves, or even blunders, and thus increase my chance of winning.</p>

<p>A few thoughts:</p>

<ol>
<li>When the opponent invites me into a sharp line, decline it. Make moves to solidify my position instead. Decline most gambits.</li>
<li>Choose boring openings whenever possible.</li>
<li>Choose openings that my opponent does not like, if I know their preferences.</li>
</ol>

<p>Is the idea of destroying your opponent's fun good? Are there any other strategies to bore my opponent so that hopefully they will lose their patience and start making inferior/aimless moves?</p>
 19192: <p>Something tangible - all things equal, if a piece is pinned or trapped, delaying the capture as long as possible can be a very small psychological advantage.</p>
 224: <p>There are a lot of issues raised here and I'm going to take them in a different order than presented:</p>
<blockquote>
<p>Is the idea of destroying your opponent's fun good?</p>
</blockquote>
<p>Not in my opinion. From the perspective of winning the game, you seem to believe that denying them fun will lead your opponent to blunder. It may against some players. However, &quot;battle-hardened veterans&quot; will have seen players who use strategies like this and are likely to just play on with no ill effect. For some folks it is the winning that is fun. So if they beat you it doesn't matter what you did during the game; the only way to deny them their fun is to defeat them. Other people have fun just playing, so there may not be an approach you can take that will deny their fun. Thus I don't think this is a dependable method for winning.</p>
<p>Additionally, I will relate a story from my childhood. While I learned the game from friends at school, after a while I could no longer play there. As my family lived &quot;out in the middle of nowhere&quot;, I had no one else to play (this was long before ubiquitous internet access) except two step siblings. They were the sort who couldn't enjoy a competition if they didn't win, but I quickly advanced past their skill level and defeated them every time we played. Thus I quickly found myself with no opponents. Unfortunately, this lasted for several years. So, making the game a miserable experience for your opponents could lead to having no one else to play. Of course, if you are better than they are and they are the sort who only enjoys winning, there may not be much you can do, except to teach them to be a better player if they are amenable to that.</p>
<blockquote>
<p>I play for two purposes:</p>
<p>1.to win the game, or when winning is unlikely, to draw the game.<br />
2. to improve my chess skills, which eventually enables me to win/draw more games.</p>
</blockquote>
<p>Others have already pointed out that the second point is at odds with your proposed strategy of boring your opponents into blunders - you aren't improving your chess skills by taking advantage of opponents' blunders. Also, relying on mistakes by your opponents won't lead you to wins all the time, as you will encounter games in which the other player doesn't make (game changing) mistakes.</p>
<p>As for the actual title question about minimizing your opponent's fun ...</p>
<p>I realize you are primarily discussing on line play. I think that boring your opponent or making them unhappy in the game is harder when you don't even see your opponent, especially if it is someone with whom you are unfamiliar. If it's someone you have familiarity with, then you may be able to play openings they don't like or that are boring and avoid sharp lines. Furthermore, none of these are inherently wrong or necessarily going to induce boredom or displeasure. If you need a draw to win a prize, they are even quite understandable. What I really want to address under this topic is over the board play, where methods of denying can fun include:</p>
<ul>
<li>Sighing, cursing under your breath, and making other noises when you discover a mistake</li>
<li>Similarly, saying &quot;A-ha!&quot;, &quot;Eureka!&quot;, &quot;Gotcha!&quot;, etc. when something goes your way.</li>
<li>&quot;Smashing&quot; the clock, especially if it is your opponent's and you do it particularly forcefully, making them think you might break it.</li>
<li>Making your move and hitting the clock so fast that your opponent hasn't even had a chance to hit the clock themselves.</li>
<li>Asking to see your opponent's notation sheet because you messed yours up. Double the annoyance if you do it on their turn/time on clock.</li>
<li>Making all your physical movements as if you only have seconds on the clock, even if it is very early in the game or after thinking for quite a while.</li>
</ul>
<p>As noted in comments, these actions could cause your opponent to register a complaint for distracting behavior that would lead to penalties.</p>
 2655: <p>I'll leave the technical details to people who have played more chess more recently than I have, but I respectfully submit that your intent is counterproductive to your stated goal of </p>

<blockquote>
  <p>to improve my chess skills, which eventually enables me to win/draw
  more games.</p>
</blockquote>

<p>With chess, as with <em>any</em> competitive game, sport or skill, at the higher levels the best way to improve is to challenge yourself against as many different opponents as possible.</p>

<p>If word gets around -- as it will -- that playing against you is slightly less interesting and engaging than watching paint dry while listening to Mr. Roboto read Galt's speech from Atlas Shrugged, people will start declining to play against you. </p>

<p>Worst case, you might wind up winning a tournament only to be politely but firmly disinvited from coming back next year.</p>

<p>On the other hand, if they find that playing with you is an interesting challenge, then win or lose they'll gladly do it again next year, and you'll be able to find out what they learned in the meantime. I personally would think that benefit is worth the low, low price of not being a tedious jerk just to win by default.</p>
 13433: <p>I recommend reading Jonathan Rowson's excellent <em>Chess for Zebras</em>, which analyses chess psychology in quite some detail.</p>

<p>One core observation is that humans do inevitably think in stories to make sense of the world around them, and chess is no exception to that. It's actually not easy for the human brain to take a fresh look at each new position (after each move) while completely discarding everything that happened before. </p>

<p>To some extent, the chess community shares common stories ("folk stories") that will shape the expectations about the ongoing game. For example, the Sicilian defense is linked with the idea of counterattacking and a bloody battle, and many players precisely pick it up because of that reputation. Many of these then don't like to play against the "Anti-Sicilians" not because they would be more threatening than the Open variations, but simply because they lead the story in a completely different ("boring") direction that is less fun to them. By picking such a variation, you may not play the objectively best line, but you can certainly irritate your opponent. Conversely, defenses like the Caro-Kann or Scandinavian are typically picked by players who want a quieter game and won't like if you play more aggressive lines, the French is associated with locked pawn chains, and so on. Of course, it's not wise to go as far as to knowingly play completely unsound lines though. Some less fun for your opponent usually won't make up for hard material (then again, many gambits bank on that in addition to their "objective" compensation).</p>

<p>The book also discusses the question of whether Black "equalizing" should actually be considered as "=" or "=+". The reasoning for the latter is that while the position will still be a draw with perfect play, it's now more "fun" for Black (who "succeeded" in the first-move advantage story that tells him that he has to fight for equality)  than for White (who "failed" in the story that he has to push for the win) and this alone will slightly increase Black's winning chances by the same logic as asked in the question (White will be a bit more likely to "overdraw" and thus make mistakes).</p>
 11629: <p>Most definitely (as in any sport) it is a good idea to play to your strenghts and to your opponent's weaknesses.</p>

<p>This requires:</p>

<ul>
<li>that you have the time, data and ability to analyze your opponent's games</li>
<li>the ability to be able to play all kinds of styles.</li>
</ul>

<p>Both of these are just about impossible for beginners though. But as you advance you should  consider this as an additional option. Mastering this is reserved to some of the best players and even among those, many players do have a certain style.</p>

<p>I would not go so far as to chose <em>boring openings</em> consistently. What if your opponent likes boring games as well? Being flexible is a good idea in chess.</p>
 12873: <p>Chess is a zero sum game, so your opponent's disadvantage is your advantage. Therefore, if you are serious and can find any (sportsmanlike) way to make them dislike the game, you should clearly take it. </p>

<p>Your first two points (declining sharp lines and choosing boring openings) are fine, as long as you won't be more bored than your opponent is. If you prefer positional systems then this will work well, but keep in mind that your opponent has a similar mindset. They will try to get you into sharp lines that you dislike. The struggle here is to see who gets their way, and often the choice of opening and be helpful in dictating the play.</p>

<p>The third point should absolutely be followed, if you're capable of playing different openings. In preparation for world championship matches, the contenders spend months going through their opponent's games, looking for weaknesses. If they find that one opening is particularly difficult, they will choose it.</p>

<p>To be clear though, you should mainly be focused on making objectively sound moves. If there is an opportunity to minimize your opponent's fun, with little to no cost for you, then take it. But don't go into a bad system just because you know your opponent won't like the arising positions.</p>
 4418: <blockquote>
  <p>I play for two purposes: </p>
  
  <ol>
  <li>to win the game, or when winning is unlikely, to draw the game.</li>
  <li>to improve my chess skills, which eventually enables me to win/draw more games.</li>
  </ol>
</blockquote>

<p>These are good goals, although you might want to add "to have fun" because if you don't have fun you are quickly going to lose motivation.</p>

<blockquote>
  <p>I do not care about my opponents' fun.</p>
</blockquote>

<p>Also good, because if you care too much about your opponents' fun you will end up losing focus and not follow your two stated primary goals.</p>

<blockquote>
  <p>Is the idea of destroying your opponent's fun good?</p>
</blockquote>

<p>No, it is counterproductive. If you start focusing on how much fun your opponent may or may not be having then this can only distract you and detract from your game. If, for the purposes of this question you are going to be truly self-centered then you cannot let your opponents' feelings, good or bad, enter into your considerations. It can only lead to bad play on your behalf. Concentrate on making the best moves.</p>
