My buddy and I got stuck with a pally tank in ToC a while ago... He goes afk as soon as he gets in, which was a bit irritating, though did not even compare to what happened on the faction boss people.
Pally tank pulls, and since I'm the healer I usually try to be nice and heal the tank. In the span of the time it took for me to cast sacred shield, beacon of light and ONE flash of light I pulled aggro on the shaman and warrior and it seemed as if the tank did not even know. He just stood there auto-attacking the mage while the other 2 mobs were beating the hell out of me, and after a few more seconds I had aggro on the mage too. People are yelling and screaming and going berserk, and this guy says NOTHING until after we all die... then he goes "sorry i just got off work" ..............whaaaaaat???
He wasn't terribly geared, he just sucked ass. The dude was using wisdom as his tanking seal and blessed himself with might. He also apparently had no knowledge of what a "taunt" was, or that it was good to use consecration as a tank. Believe it or not we managed to teach him how to tank with only 2 more wipes on the faction peoples and finished the run cleanly lol XD