If all guys did, all guys would be so totally shallow!
Probably just to scare very young teenagers away. Lol.
Even though I've never had it, so I can't be certain.
As a girl, I like the guys always hanging out with their friends, not always looking at us, that creeps me out. I have a big crush, and he rarely looks at me, its better that way, unless you're dating her, THEN if you look at her it probably won't freak her out.