I've been hit so hard in the head with that a couple of times, both upsetting someone when asked what kind of expectations went along with a date, and having people get upset with me because they thought my actions indicated dating interest when I was just being friendly. I can rarely spot an indirect flirt, I like verbal flirting in both directions -- and yet, I'm really bad at it.

That might be because I'm fairly conflicted about my own availability and desirability, though.