It depends on the attitude and feel of the group for me. If I am in a group with people who I feel are generally doing their best and aren't being jerks, then I don't mind staying until the group decides to call it quits together.
I had the worst H ToC Pug run last night though. We had two DPS from the same guild who from the very getgo were telling people how to play their class. I generally ignore these remarks and do my thing, because I feel that I have a very solid understanding of my class and how to play a tank.
Well, the crap hit the fan several times during the instance, and some people made very stupid mistakes. The ret pally, who was our other DPS that was not in the guild with the other two, BUBBLED me during phase 2, completely resetting my agro table and making me not be able to use any abilities. Although it was quite a stupid mistake, crap happens, and I wasn't upset. However, the two other DPS trashed him. We wiped a couple more times and then the two DPS started blaming the healer.
Regardless, we finally get to the Black Knight. We wipe again, and one of the two DPS kick the Paladin, apparently because our reason of failing was all of his fault (according to them). They replace him with a "good" DPS, and we go in again. Wipe two more times. Then the two DPS say "Fail, worst group ever! You guys suck!" and leave.
Again, I try and avoid these kinds of comments, but it got to me this time. I promptly messaged one of the guys that left and asked said something like, "Are you guys really blaming this on me? We did have a few weak links, but I sure as heck did my job". He responded saying that I was having a hard time maintaining threat? Seriously? The only time I lost threat was when the paladin bubbled me, and there was nothing I could do about that. I then told him that I hope that his blame it on everyone else attitude brought him far in life, and /ignored him.
Was I wrong? Regardless, I think I've decided that I am giving a 2-3 wipe limit when I'm grouping with douchebags. Or perhaps I will kick the jerks and find some decent mannered people instead.