I was recently healing in a Vault of Archavon PUG raid, and although we wiped on Emalon (but killed Koralon) it wasn’t the wipe in itself that made me see red, it was the behavior of the top DPS.
During the kill of Koralon several of the raid members noticed with respect how one of the hunters was pulling out impressive amount of DPS. And by impressive I mean light years from normal PUG behavior. Usually I’m happy if everyone is above 2k DPS, and here is a hunter doing 5-6k. When inspecting him I saw he was sporting top-of-the-line gear from Trial of the Crusader, so he likely outgeared everyone there.
Emalon the Storm Watcher (for those unfamiliar with the fight) is a boss that comes with four adds. At certain times he will cast the spell Overcharge one of these adds, and unless you kill that one within 20 seconds it will explode and wipe the raid. Normally this is a piece of cake, although you usually have to have someone start screaming at everyone to run and kill the add. Proper raid people will have an addon with timers so they can switch targets on the second he does the Overcharge, but this is a PUG.
We killed the add several times during the fight, but when Emalon started getting low on health we for some reason didn’t manage to kill it in time, and it exploded and wiped the raid. Ensue frustrated screaming, yelling, finger pointing, and generally blame everyone but themselves for being such crappy players.
When checking the DPS meters (Recount addon) the hunter was still number one with impressive 6k DPS, closely followed by a warlock. That is great.

What Recount can also show you (beside what abilities people used) is who they did damage to. Turns out the hunter did 1.68 million damage, but only 17k of those was on the add.
So what you have here is a person so fixated about doing maximum amount of DPS (and by the look of it the warlock was not close behind) that he purposely ignored to switch targets (and lose DPS) to kill the add, and the raid wiped.
Yes, you can do 6k DPS and still suck as a player!