I've been going back to running random heroics this week, and while none of them were exactly awful, none of them were truly pleasant experiences either. In particular there were two types of behaviour that got on my nerves a lot.
Firstly, dps pulling for the tank. I know, people have been complaining about this almost since the dungeon finder's introduction, but I honestly didn't actually see anyone doing it all that often. In the past week however, nearly every pug I've been in has had a dpser doing it. Mostly it's dps warriors, but other classes have been guilty of doing it as well. Only today I ended up healing a heroic Halls of Stone run where the mage started blizzarding the first group of trash mobs almost as soon as we had zoned in. The tank and I just took a step backwards and out of the instance until the fighting was over and then came back to res the culprit and those he had taken with him. What was he thinking?
I refuse to believe that so many people get off on pissing off tanks and reducing their numbers even further; are they just all that ignorant? Here's a hint: if you're running headlong into groups of mobs without being the tank or truly being able to finish them all off on your own, you're being stupid. You're effectively trying to kill yourself and relying on the tank or the healer to bail you out. I usually don't intentionally let people die for being stupid, but if I see that the tank doesn't want to babysit you, I won't do so either. We're here to fulfill our roles within a normal five-man dungeon run, not to serve as your personal bodyguards while you hurl yourself from one suicidal situation into the next.
The second annoying behaviour that I had to deal with repeatedly this week is sort of a reaction to the former I suppose - tanks treating the instance like a race to the point of stupidity. I'm not talking about fast pulls here, I'm talking about cases like the tank I had in heroic Utgarde Keep who would aggro a group of mobs, hit them once, and then run off into the next room while the mobs beat on the dps who were actually trying to kill things before moving on. News flash: you're supposed to actually tank things, not just aggro them once on the way to the last boss!
I have a limited amount of understanding for how "tanking" like this might serve as a sort of defense mechanism against the first peeve mentioned in this post, but the tank playing badly instead of one of the dpsers still doesn't make the run any more enjoyable for the rest of the group.