first impression she's a dog.
a lot of guys see a girl who looks like a cunt and think
a: challenge
or b: got to beat my aa
you gotta understand the difference between aa and a read of the person. in the book blink it demonstrates people can often get a good idea of what someone's like in a split second (hence body language important/self coming through).
go for a girl who's a:fit and b:nice and friendly looking.