I have not had any rude groups yet, even when I have said I haven't done the dungeon. But that is probably true for most people I am grouping with since I am only in the high 20s so far. I also have tanked in other MMOs, so I easily saw which of my abilities are most important and how they should be used. Newer tanks will have a steeper learning curve for playing their class. My only bad experience so far was a not so good healer that would only start healing me when I got to around 25-40%. Until that point, he was spamming his stupid rock spell to damage the mobs. :P