For me, it's 90% attitude/actions and only about 10% looks. Imo, a person is sexy when he/she finds a way to be and act that suits them and allows them to be themselves; when the personality inside can be radiated outward by a person's manner and actions; THAT is sexy. People need to be truer to who they really are, instead of conforming to some homogenized MTV-promoted extremely narrow vision of "sexy/beautiful" which most people can't pull off anyway and which is so dime-a-dozen and UNINTERESTING that, to me, it's boring and not sexy at all. People who try and emulate that "style" (if you want to call it that), aren't sexy (to me); they're boring followers who don't even realize how boring they are. This kind of narrow vision promotes the idea that there is only one way to be beautiful (for men and women, but mostly for women) and anyone who doesn't (or can't) fit into those strict criteria isn't worthwhile. It's also an EXTREMELY sexist vision, imo, since female beauty is judged on the most horribly superficial basis -- 95% airbrushed looks, 5% the ability to follow some choreographer's instructions -- the only way a woman can be sexy is if she's extremely thin, extremely tanned, slathered with cosmetics, half-naked and rubbing herself against some guy's car
My prefered list of "sexy" traits includes: HUMOR/silliness, humility, curiosity about many different topics (i.e. science, religion, history, art), independent thinking/opinions, thoughfulness, intelligence without arrogance, simplicity, dressing onesself in a way that suits your natual looks/body shape/coloring... etc.
PS -- sorry for the rant. THIS is why I should never watch MTV; and I NEVER do, but my fiance' is here now and he likes to watch it, so I sit there making comments (both subtle and not-so-subtle

) about how sexist and disgusting and TALENTLESS I find 9/10 of these people to be and how interesting it is that there isn't a single overweight or plain-looking girl who can sing well these days, hmm....