I used to be afraid of checking girls out, because I'm always afraid they'll think, "God, look at that creep. Why is he looking at me?" But I went past that because I know I'm not doing anything wrong, I'm just being a man, and a man just can't help from admiring a beautiful girl.
If you think I'm a creep, that is just your opinion. Most of us just like to look. I'd say 99.9% of men just look at you and think "Wow, she's cute."
Of course, with your negative experience in the past, you'd have generalizations about why we would check you out. But trust me, most of it are just innocent stares.