@ Everyone saying to leave:

The problem with this is Blizz is tracking how many times you personally abandon a RDF PUG. People who tend to leave groups or kick members will find they still have to wait the fifteen-minute grace period when others can boot jerks instantly.

In other words... it's in your best interest to stick it out. Put the trash-mouths on /ignore, tell the group you're doing so (or better yet, whisper one of the goupmates who is acting the most maturely instead, so as not to let the abusers see you're doing it, as they are after all looking for attention). Then just run as normal. If the group is paused because of the arguing, go make a sandwich or something. If you're in a hurry, say something about it. Don't be That Guy who initiates pulls when the tank isn't ready though.... even if the tank is the one who initiated the verbal PvP (love that phrase!)

A few nights ago I did a dungeon with a bickery hunter, who kept making snide comments about how crappy I was as a healer since his pet kept dying, how terrible others' dps was, etc etc. Constant bile spewing from his general area. When I snapped and told him his pet was his responsibility, the tank whispered me and told me to ignore him because he's always like that in groups... turns out the tank was his wife... I felt so bad for her :(