Talking to complete stranger chicks on the street ain't easy!!! Some fine chicks have a real mean streak and kinda enjoy ripping nervous guys to shreds. It takes balls.
I don't know about a mean streak. It's the same as how someone might act like a dick when some crazy motherfucker at the gas station starts trying to tell you about how he needs $2 to take the bus to get to his mom's funeral. After a while you just get tired of people approaching you that you want nothing to do with, and the easiest way to cut it short is to be a dickhead (or a bitch).
I'm sure it's exhausting having guys who aren't remotely attractive or interesting decide that they should "just take a shot" cause they have "nothing to lose", when in doing so they just waste your time (and their own).
Of course if he does it enough it's going to work eventually, so, you know. Run that game, bro.