Ugly. Plain and simple.
Also, getting away with plain stupidity just because they're hot, and clinginess just screams insecurity. They are both miserably unchangeable. Nasty turnoffs they are.
All other stuff is trivial because you help them change it or learn to cope.
EDIT: Yes, that's right, PLEASE thumbs down me if you're an ugly girl. I reject them hitting on me almost everyday. So, it's time for your revenge =]
Oh yeah I almost forgot, I don't like a smug people, like me! =D