Why do women think they're too good to speak to men?

I'm a 21 year old guy, im fairly handsome, but not outrageously great looking though. I dress clean and im hygenic. Now that ive gotten that out of the way I've noticed that a lot of females act as if they are too good to even say hello to me. Its not only me it happens to my friends too. I may start casual conversation with a girl, being respectful and everything, and she'll blow me off as if im trying to ask her out like shes Gods gift to men even when shes NOT that attractive. Whats wrong with women? Why do they think they're better than men? Why are they so rude even when they're NOT that attractive?