Below, some things that women might think are sexy, but men don't!
1) Overtanning. Think Katie Price. Tans are cool; tans gone overboard to the extreme definitely are not, not to mention bad health- and beautywise long-term (what with cancer risks and premature skin aging from sun exposure). A nice tan doesn't leave you looking orange or with weird, splotchy edges near the hairline. Usually, going one or two shades darker (possibly three) looks more "natural" - anything significantly darker just screams "overtanned"!
Most guys want it both ways...they love how women look with make-up, just as long as it's not "overdone". The idea is, as long as the make-up is blended well and she still looks recognizable without it, it's all good!
Bad.4) Fake eyelashes. Notice a theme here? Now, I have nothing against fake eyelashes (have worn them myself now and again), but if you do wear them, try going for more "natural" looking ones (ones that have different lengths or are in separate "pieces", not ones in a strip that are all one length). Fake eyelashes that are "overtly" fake are definitely considered a turn-off to most guys. Also, secure them firmly in place on your lashline - nothing's worse than having them fall off or come loose (unbeknownst to you) in the middle of a date!
6) Fake nails. Men don't like the idea of anything overtly fake on a woman (even though they like the overall "look" that those "fake" things provide!). Most guys don't care if women have fake nails, again, as long as they look natural. Anything too obvious or that screams "press-ons" definitely wouldn't be considered sexy!