In my personal gaming experience, I would have to say that most of the time I become upset, angry, annoyed or feel the need to take a time out, it is because I chose to run a dungeon with a pick-up group. Whether I'm tanking or healing, I inevitably run into people who seem to have no regard for other players.
As an example, I have a strong policy about my resurrection ability. I feel that if you die, whether from a stupid mistake of your own or a legitimate reason, you deserve to be resurrected.
On the other hand, if the entire party wipes, and no one had a soulstone or self-resurrection available, I believe everyone should run.
Sure, if you have to hit the washroom or someone comes to the door, I'll run with everyone else and pick you up after, and that's no problem.