A car or household lubricating oil, such as WD-40 or 3-in-One oil (both are brand names in the UK) will dissolve the label glue.
Put one or two drops on the glue residue and rub with, say, a paper towel for a few seconds, and the glue should start to come off.
I haven't tried using vegetable oils, so I don't know if any of those will work.
sustainability.stackexchange.com/users/450/Ciaran McHale
I just realized that direct heating with a flame does a pretty good job.
Boiling water wasn't enough, but heating with a flame seems to do the trick.
After heating, wiping with a rag takes the glue off.
There is still the smallest amount of residue left after the flame-and-wipe.
I'll give @Claran's oil suggestion a try and compare the results.
sustainability.stackexchange.com/users/28/Laizer
I soak in water and use a steel sponge.
Might be interesting for those who don't want to play with fire.
sustainability.stackexchange.com/users/96/mart
The best solvent I have ever found for stubborn materials is (surprisingly) "NZ tea tree oil" .
It also does not seem to harm most surfaces - a paradox.
It's not known to be especially poisonous - it is sold as a health product.
The genuineness of the health claims made for it are unknown to me, but it seems close to the ideal solvent to have on hand.
Many sellers here - be sure it is from NZ tea tree (really).
It's never cheap, but as a solvent a tiny amount is enough for most purposes, when all else fails.
And, the result smells good :-).
One seller here as an example - good website name :-} ie http://teatreeoil.co.nz/ .
This is not the same as Australian tea-tree oil, which is derived from a quite different plant and is nowhere near as good as a solvent - sadly so as it is much cheaper. .
Eucalyptus oil is extremely good.
Similar overall to NZ tea-tree oil.
Not as good as a solvent but better than most.
Inhale fumes for blocked chest.
Put a drop on a spoon of sugar for internal use.
May or may not work
BUT those were among my (long ago) childhood remedies.
Ethyl alcohol, or meths (in NZ it no longer contains added Methyl alcohol despite the name).
Not as good as above but often useful.
Safe enough in small quantities (do not drive and label dissolve :-) ).
Acetone often does well.
Likes dissolving some plastics.
Methanol (wood alcohol) is often effective.
Nasty stuff and very poisonous - but the drop or so usually needed as a solvent should be easy to use safely.
Carbon tetrachloride was the mainstay of drycleaners for many years.
A carinogen, absorbed through the skin and a liver poison.
Charming.
Still has its place if used sparingly in small volumes with great care.
Methyl Chloride !!!!!!!!!!!!!!!!!!
Nasty poisonous stuff.
Dissolves some things really well.
Will chew apart set epoxy (with violent cracking).
Has its place.
Use with extreme care.
sustainability.stackexchange.com/users/318/Russell McMahon
Toothpaste works reasonably well with a little elbow grease and an mildly abrasive pad.
sustainability.stackexchange.com/users/1209/F. Wingenroth
Mayonaise works on most solvents -- any oil emulsion works.
Put on and let soak.
For the 10% or so of stuborn labels I find that mineral spirits or diesel fuel work.
sustainability.stackexchange.com/users/400/Sherwood Botsford
I up-cycled a glass liquor bottle into a drinking glass (by means of scoring, heat-shocking, and polishing).  What I'm left with is a lovely glass with some very stubborn label glue on it.  How can I get rid of the glue?  Big bonus points for something that doesn't involve nasty chemicals.
Getting rid of label glue
sustainability.stackexchange.com
<recycling><upcycling>
sustainability.stackexchange.com/questions/741
sustainability.stackexchange.com/users/28/Laizer
Methanol and acetone can remove glue. Toothpaste, mayonnaise, WD-40 or 3-in-One also work. Heating with a flame or soaking in water and using a steel sponge are also recommended.  Tea tree oil or eucalyptus oils are natural alternatives. Solutions include methanol, acetone, heat, steel sponges, toothpaste, oil-based emulsions and lubricating oils.
Methanol and acetone can work. Direct flame heat can work, as can a steel sponge soaked in water. Toothpaste, mayonnaise, household oils, tree oils and emulsions work well.