This one is a bit of a doozy. First off, a little bit of VA, as volatile acidity is referred to, can really make a wine’s bouquet explode with intensity and depth, so a little is usually good. VA comes in two main forms: the first version is acetic acid, and gives wine a vinegary smell.
Over time, the acetic acid interacts with the alcohol and creates ethyl acetate, which smells just like nail polish remover, mostly because it is found in most nail polish remover! Now, I wouldn’t go around drinking nail polish remover -- that would be very bad -- but you don’t have to worry about drinking wines that exhibit this form of VA. In fact, many of the greatest dessert wines ever made exhibit noticeable VA!