I only leave when someone is exceedingly rude to me. Nothing else really matters. I don't mind if we wipe over and over again -- I find that the chaos can be fun sometimes, and I'm not pressed to get something down on the spot. I like to take my time with things. I don't even mind if we end up with a bot, because it makes it more of a challenge for 3 or 7 people to clear something.
As a rule of thumb, I generally don't say a whole lot in dungeons unless other people are already talkative, and I try to ignore snotty remarks until it becomes clear that someone's attitude is affecting the dungeon/raid. I hate when players start getting upset after a single wipe due to a mechanical issue, or they start berating others without reason. I find that actions often speak louder than words, so...

-As a healer, if I find that someone is rude to my party or myself, I won't leave unless the tank does. If someone starts trying to speed run ahead of the tank, I simply won't heal you. I don't want to die, and I don't want someone to think that it's okay to paper-tank when it isn't.

-As a tank, I'll slow down and walk through a dungeon if you're rude to me. I'll let the person leave and take their penalty or attempt to vote-kick me, but I'm normally not alone when I queue, so the vote-kick won't pass anyway.

-As a DPS, I'm far more quick to leave because I have little control over how the dungeon is run, and another DPS is bound to show up the moment I leave anyway. I find it more offensive when a tank or healer is rude than a DPS, but I also think that they have a little more responsibility not to be rude because they are proponents that a party cannot do without.