misdirected aggression. People often handle rejection poorly, and it's pretty much a learned skill to redirect it
Ugh. What a tool. The craigslist guy, that is. Just because you're nice to someone doesn't mean they're attracted to you and have to sleep with you.
I know. If they're actually "nice" like they think they are, they'll find someone they like who actually wants to sleep with them and just be a dámn friend to the other person.