The way girls look at me?

If they stare for longer than 30 seconds, they might be interested. Either that or you have spinach in your teeth. But generally, these girls are probably just looking.

Well, wouldn't that be qeird if some random girl would walk straight towards you and hit on you? I think that's what guys do... (just joking!) Anyway, if they stared for more than five saconds (that's the average time we look at people in the street for example... people we don't know in general and we have no particular feelings towards them...) Plus, you said you're used to getting stared at by girls so why do you find these girls staring at you weird? :/ Most of them don't even want to get to know you, to be honest... They just want to freaking stare at you for the rest of their lives or just, you know, have your children... (again, just kiding) Nevertheless, I think that's where my thoughts on the matter end... I hope I helped even a little bit! :)

It could be you are so stunning, like shockingly stunning that they are intimidated to talk to you. It's a known fact that when people are amazingly good looking, really, really good looking, they are afraid to talk for fear of rejection. Must get lonely being really, really good looking.

I wish I was really, really good looking...but I'm really, really ugly.

It depends what they do when they make eye contact. Most of the time if a girl smiles at you after making eye contact or raises her eyebrows it means she is interested. But that's not always a sure sign because some people just smile to everyone because they are so happy with themselves. Girls will usually do subtle things sometimes consciously, and most of the time subconsciously when they like a guy. For example if you're at a place and a girl keeps staring at you and playing with her hair that is an obvious sign that she wants you to approach her and talk to her.