Acetone Technique

Acetone catalyzes in the presence of copper and oxygen, which generates oxidation (from the reduction of the acetone) and heat.

True acetone won't hurt pure silver but most silver coins minted have some copper content. Using actone on these will create pitting as the acetone will react selectively with the copper in the alloy. Also once catalyzed the reduction will continue until all of the acetone is comsumed, and you are left with a layer of oxidation which will react with moisture and oxygen to sustain the oxidation reaction.

Also once you remove the passivity layer on a coin's surface you expose a whole new surface for fresh oxidation. Depending on how evenly the passivity layer was removed the coin will oxidize evenly or unevenly.
Fingernail polish remover typically has some surfactants and fragrance mixed in, even the "100% pure" stuff. The surfactants are more likely to be residual and need to be removed.

Acetone is also an irritant and can cause respiratory damage. I used to have to do lab work under a hood when I used acetone.

Distilled water is available in every grocery store and Wal-mart for less than $2 per gallon. Use the water sold in the baby section as "nursery water" as it doesn't have additives put in after distillation.
Best bet is to use some distilled water with some dish soap and rinse thoroughly after.

The reaction would be infinitesimally small over a period under which a collector would be using acetone. The tiny amount oxygen produced would rise into the container air space and definately have NO effect on the coin. I have personally soaked every coin composition for a week or longer with zero adverse effects, i.e. no pitting. I know Carl has pushed this to weeks and included sunlight with no ill effect.

Are you a chemist or just a googler?

Sometimes coins are dirty, they just look like it because they are corroded or have environmental damage. I have used a q-tip on coins when they are soaking in distilled water rather than acetone. I found that 90% alcohol is good for taking off dirt as well.