Check the Attitude at the Door

When is it right to point out that someone's behavior is a turn-off and they should consider a change of attitude?

I was on one of my usual social sites this evening and I started a conversation with a guy I've talked to online off and on for a few months.  At one point he jokingly says that he is still mad that I have a boyfriend now.  I tell him that it wasn't like he was the only one that was showing interest in me.  He then says (paraphrasing here) "It's okay, it looks like I am going to be stuck being single for a long time so I might as well just get used to it."

Hold it, back up for a second, read that again to yourself and then read it out loud.  If you were to hear someone say something like that to you and you were single, would you still want to go out with them?  If you do, I'd have to call you naive or say that you're being way too nice.

I was very sorely tempted to say back to him "See, this is why you'll stay single.  You say something like that and you come off as trying to make the other person feel guilty so they'll go out with you."  However, I kept my mouth shut and it was appropriate to do so.  I haven't met him in real life so he's not really a friend, at least by my standards.  The question still remains, when is it appropriate and with who?

I think we're all guilty of pulling a stunt like this at some point or another for whatever reason, but if it is consistent behavior then we should be called on it.   Unless they manage to find someone who is naive enough to not catch that behavior and also has the patience of a saint, most folks are going to take one look at that and be turned off immediately.  I should know, I was once that naive person that put up with that sort of behavior, but not now, and not ever again.