Some persons, myself included, are really sensitive to certain types of nail polish. Something in the polish bothers my eyes and I would really hate to start out a flight with itchy, red eyes. If the smell is strong enough, I have trouble breathing so I can really empathize.

I have changed seats on a train because of a woman painting her nails. However, on an airplane that is not usually an option. Speaking to the flight attendant seems preferable to fake retching or a fake asthma attack.