for me it's eye liner... no matter how well i clean my eye's there always
seems to be a small amount left behind. proof of this is when i think
i'm done cleaning my eye's i take a q-tip and go over where the liner was,
and there is always a black spot on them!!

bright or really dark nail polish use to be a problem, but since i started
using a clear coat first, it doesn't seem to be a problem anymore!