I can't express how good it feels to see that said

I can't agree more. That sort of behavior is incredibly hurtful. It's one thing to genuinely come to the conclusion that you're not really interested, but it's quite another to string a person along when you KNOW you aren't interested in them. With all the false and mixed signals, you'd have to be a frigin mind reader to tell if someone's interested or not. It murders your confidence, and leads to one of two decisions, 1) stop flirting altogether and end up alone and miserable or 2) flirt with everyone all the time, whether they seem interested or not, even if you're in a relationship, since anyone, even the person you're invoved with could just be playing with your feelings. Not a good choice.

And people wonder why you get the jerk/doormat binary.