I know the saying "all's fair in love and war", but I don't ****block any guy, ever - and I don't think that any guy should ****block another guy if the other guy is a friend (unless he's blocking you!) or the other guy is on a date with the woman in question. I try to respect other men and treat them in a manner that I'd want to be treated myself. That said, I will wait for a woman to dismiss a guy or get away from him (and I don't mean her just going to the restroom) and then make a move. I figure that if a woman is with a guy she likes, I should take it that and leave 'em alone - good for her, good for him. If she's content to sit with a guy she doesn't like, she's either too polite, too stupid, or too much into scamming drinks off of him for me to care - in any case, she's not for me.
On the politeness thing, I see far too many women who - in my opinion - get trapped in a conversation with a guy who seems to be way over his head. The body language speaks volumes if you pay attention. The paradox of this is that the longer the she lets the guy sit there, the more he thinks she's interested and the more he feels that he has a 'claim' on her and that no other guy can talk to her. I've coined the term "
squatters" for guys like these
In addition to the direct ****blocks you see - i.e., just cutting right in, there are less direct methods I've seen... the guy who tries to join the both of you - in a 'just being friendly' way when you're on a date, the guy who intercepts her on the way back from the restroom, the guy who motions that he wants her number while you've got your back to him, and the guy who sends her a drink right under your nose.