Every wine drinker I know maintains at least one wine-related prejudice or another—whether he admits it or not. One friend, for example, abhors drinking white wine while another eschews all rosés (he has labeled them "Pepto de Provence.") Yet a third disdains Riesling on account of the bottle, which she calls a "needle nose." (She's a former fashion editor—of course.)

A view of Bar Boulud's tasting table in New York City. E. Laignel

I have a wine prejudice of my own: I simply hate wines by the glass. But unlike most prejudices, born of ignorance and fear, my prejudice was acquired through experience.

Foremost among my glass-hating reasons is price. Wines by the glass are almost invariably the worst deal in the house. After all, the conventional rule of thumb calls for the price of the glass to equal the wholesale cost of the bottle, plus, often, a few dollars more. And with five glasses in a bottle (or four, at a more conservative measure) that's a profit margin so large that only the greediest restaurateurs would dare to charge a similar markup on a full bottle. As Michael Madrigale, wine director of New York's Bar Boulud, put it: "The wine-by-the-glass program pays for corked bottles and when wine gets sent back. For most wine directors, it's the profit engine of a wine list."

And yet no one seems to be protesting. In fact, there are more and more places that focus on wines by the glass. Take the number of wine bars that have opened in this country in recent years. (Wine bars are all about selling wine by the glass.) In New York alone, 69 new wine bars opened in 2010 as of late summer, making a total of 237 in the city. Many restaurants feature very large by-the-glass offerings, like Fleming's Steakhouse, which famously touts its "100 wines by the glass" program at all 64 locations in 28 states. Fleming's has even trademarked the amount, calling it "The New Fleming's 100" (which sounds to me like a Nascar event).

My sister in Dallas loves this sort of program. She loves to order wine by the glass because "you can try a bunch of different ones and if you don't like one you can throw it out—or finish it off—and try another." When I informed her that every glass she consumed—fully or otherwise—was actually funding the entire cost of the bottle, she affected a level of indifference that could best be described as Texas-sized. "I don't care. I would never bother to add it up," she said.

This is no doubt an attitude that restaurateurs hope all their customers will adopt. I suspect that the same people who aren't considering the cost of a glass aren't thinking much about the condition of the bottle either. They're unlikely to ask the waiter or bartender how long it was open, or for that matter, how it was stored. Yet both of these facts are tremendously important. An open bottle of wine on a warm bar deteriorates more rapidly than a bottle stored on a refrigerator shelf, while a wine open for five days or a week will taste very different than one just opened that day.


Five common by-the-glass offerings that I'd gladly buy by the bottle

Pierre Moncuit Blanc de Blancs Brut NV Champagne, $35

Although I'm not a fan of wine by the glass, I'll make an occasional exception for Champagne. A glass of Champagne is the best way to begin a meal or just about anything. This is an elegant, well-balanced and truly delicious Champagne from the famous Clos du Mesnil region. The Pierre Moncuit wines are still a bit under the radar—and accordingly priced.

2009 Pazo de Señoráns Albariño, $25

I've seen more and more Albariños offered at wine bars by the glass (could Albariño be the new—albeit more characterful—Pinot Grigio?), but this bright and lively Spanish white is one of the very best. It's bigger and richer than most Albariños, with a pleasing mineral edge.

2009 Château d'Esclans Whispering Angel Rosé Côtes de Provence, $16

It's become quite commonplace to find multiple offerings of rosés by the glass. This Provençal wine from all-rosé producer Sacha Lichine is a classic of the type: fruity and bright with a dry, almost spicy finish.

2006 Ladera Howell Mountain Cabernet Sauvignon Napa, $70

William Sherer, wine director of Aureole in Las Vegas, told me he can sell a "luxury Cabernet" for "up to $25 a glass." But what about a "luxury Cabernet" that's only $70 a bottle (cheap by Napa standards)? This one is dense, rich and well-structured with lots of currant and dark-berry fruit.

2009 Saracco Moscato d'Asti, $18

One glass is about all I want of any dessert wine—with the possible exception of this wonderfully sprightly Moscato from a top Piedmont producer. It's slightly sweet and slightly effervescent with lovely peach and floral notes. It's the perfect accompaniment to fruit or fruity desserts. It's also only 6% alcohol, which means you could have more than one glass—maybe two.

Of course, you also have to depend on a waiter, or sommelier, to find all this out. Sometimes their information is accurate—and sometimes it's not. I can't count how often I've asked about a particular wine sold by the glass and been told the bottle was "just opened" when it obviously was not. Or I've heard an even less reassuring phrase: "It's only been open a couple of days." The latter reminds me of what my local police lieutenant once told me: "Every drunk driver I've ever stopped has never had more than two drinks."

This doesn't mean that some wines aren't actually better the second day than the first—they tend to be youthful tannic reds such as Cabernet and Shiraz—but the vast majority of wines sold by the glass will be compromised by time spent in a long-open bottle. The fruit will flatten out, the acidity dissipate. This is particularly true of older or more delicate reds and fresh, young whites.

Still, some wine-dispensing systems are sold with the assurance that they can keep an open bottle of wine fresh for a month. One is Enomatic, a popular self-serve wine-dispenser, with over 1,000 machines in use all over the U.S. According to Eleonora Berti, marketing and communications manager of the Italy-based company, the Enomatic system is certified to keep wine fresh, using argon gas, "for over three weeks." Did they recommend that certain wines should be kept on the system for a shorter time? "I think a shop should sell a wine in three to four days," said Ms. Berti, "Otherwise perhaps the shop should close."

I encountered the Enomatic system for the first time recently at Clo Wine Bar in New York. Clo offers its wine by the four-ounce pour (five ounces is the standard wine-by-the-glass amount) at prices that range from $11 (2009 Pieropan Soave) to $51 for a taste of 1990 Chateau Musar (the great wine of Lebanon). The Pieropan is a favorite of mine (it costs about $15 a bottle, retail). I asked a nearby "attendant" at Clo how long the bottle had been open. (With most Enomatics, there aren't really waiters; you buy a card and serve yourself.) "A couple of days," he replied. And the Musar? Less than a week. But I needn't worry, he added, "All the wines are under a blanket of gas."

What about the 2008 Grüner Veltliner from Rainer Christ? I asked, moving down the line to a bottle of wine from a top Austrian producer. (With Enomatic, all the wines are in a glass box; you push the lever to release the pre-determined amount.) A couple of days, came the reply. The same was true of the next bottle and the one after that. Was there anything that had yet to be argonized? There wasn't. So I purchased my four ounces of two-day-old Grüner ($11). It was clean and bright, but the aromas were compressed. Were they hiding somewhere under all that gas?

When I put the question to Brian Smith, Clo's manager, he answered, "Aromatics are probably the first thing to fall off on wines on the machine."

But beyond issues of argonized Austrians and two-day old bottles is the perpetual by-the-glass question of portion control. While the Enomatic system allows restaurants and wine bars to regulate a specific amount, a glass of wine can range from four to six ounces depending on who's doing the pouring and often no one, including the waiter, knows how much is actually in the glass.

This is what Mike Shor, an economics professor at Vanderbilt University in Nashville, Tenn., found in his 2007 study on restaurant wine pricing. Prof. Shor, who teaches classes in pricing, examined the wine list prices of major Nashville restaurants and ranked them according to bottle markups. (He stopped going to a few of the restaurants as a result.) Prof. Shor couldn't do the same study for wines by the glass, he said, because his students reported that the wine poured varied wildly, between four and six ounces. There was, however, one consistent theme, according to Prof. Shor: "The cheaper restaurants issued smaller pours. The more expensive establishments gave a bit more."

Perhaps this was what Belinda Chang, wine director of The Modern restaurant in Manhattan, had in mind when she told me that she liked fancy wines by the glass (she called them "luxury wines"). Ms. Chang, whose by-the-glass offerings are fairly priced, recently spent $37 for a glass of Dujac Chambolle Musigny and said that she would spend even more for a truly special wine.

I'd be inclined to rethink my prejudice if more wine directors adopted the approach of William Sherer, the wine director at Aureole in Las Vegas, or Michael Madrigale at Bar Boulud in New York.

In addition to his regular by-the-glass offerings. Mr. Sherer sometimes features wines that he purchases at "close out" amounts and he passes the deals along to his customers. Take, for example, the René Geoffroy Cuvée Selectionée Champagne. The normal wholesale cost of a bottle of this top, small, quality Champagne is around $40, said Mr. Sherer, but since he bought it for less than $25 a bottle, he prices it at $18 a glass—which I think qualifies as charity work in that town.


Perhaps that is how even the most deep-seated prejudices can be overcome, through good intentions and an exemplary gesture or two, all accompanied by a great glass of Burgundy—purchased at cost.