Hm, well, I can answer a few questions I think... and take a guess at the other ones, lol!
The girls who are sleazy and unfaithful get a lot of guys... but guess what? A lot of those guys only want sex, so yup, they just both get each other a lot. (Then people wonder why those guys get all the girls and those girls get all the guys... those types just want anyone, and get each other a lot, lol). Also, people at college usually act just like you describe: only wanting sex and being unfaithful. Of course, not everyone is like that at all, but you do see those types more at college.
As for meeting guys who only want sex, well... I'd ask where do you usually meet guys? If you go to parties a lot, then you tend to get one type of guy instead of, say... going to the library, lol. Or some extracurricular club at school. Try meeting guys at a different spot. And keep looking, because there ARE other guys out there!
Also... well, don't ask me why I'm getting this vibe, lol, but if you tend to wait for a guy to approach you, you may want to bend the rules a bit and start talking to a guy that interests you for once. I know, this goes against all the official rules of meeting guys and dating and whatnot, but who knows? It might work out better for you.
Hopefully something here helps, and good luck to you in the future!