I've run a full swing of super bad to super good.
Worst one recently was a boomkin (who queued as the tank) and holy pally in H VH. Both superbly geared and me and my two friends, on our alts, not so well. We're pulling 4k dps, which isnt terrible, but the boomkin decides its time to start bad mouthing people. Paladin of course plays along with the boomkin in bad mouthin. Well lucky us we get erekem. /w 2 friends kill the adds first then don't touch the boss. OH SNAP we wiped. I proceeded to the oh damn how did that happen game. Paladin gave some excuse for not being able to keep the boomkin alive while it was obvious he wouldn't have survived (i've seen 40k hp tank nearly bite the bullet on him). I payed my friends repair bills but it was worth it and then some. Gonna play the role of jerk? Fine, its about to be your waste of time.