Why don't girls look at me or show any interest in me?

i just don't get it, i'm a good looking guy and all but girls never look at me or they go 'ewww' or they completely turn there head when walking past me to avoid looking at me or they just give me weird looks. Like I smiled at a girl the other day i thought was hot and she just gave me a dirty look. I try and i try. Don't know what it is.