Teenage Boys, and young men...tell me truthfully.?

I mentor a group of teenage girls, and I'm constantly telling them that teenage boys are getting tired of slutty girls. A lot of the girls seem to think that if they dress slutty and act slutty, that boys will like them more. So tell me guys, would you prefer a nice intelligent young lady who carries herself well, and does not sleep around, or a half-naked tramp who has been with every boy in school? Please answer truthfully and honestly.