These stories needs to be told (also at the end, more fail PuG stories)
There was the story of the imbahunter, who used MD on himself on mobs that I had not picked up, then adding "i will try and dps less on the next pack so you can get aggro". How about you just frikking shoot at the right adds? And a little extra tip from me to you: when you fight General Bjarngrim it really helps if you gun down the adds first... you know, like the tank tanking them told you to.
It was the same hunter who -or so he told- had a healing alt "so i know how to heal", so he didn't need a healer and a tank telling him when the healer needed mana, before he was allowed to pull the next mobs... or bosses. 15% mana is plenty for a Disc priest it seems.
Then there was the glorious paladin. I loved this guy. I really truly did. He was the 5th dps in our otherwise guild-dungeon run. He turned up in tanking trinkets, +spellpower shoulders and a magnificent weapon to boot: Cleaver of Diligence (I believe it was, it was green and no higher ilvl than 170). Now that was all fine and dandy. (well not really, he was clearly using his trinkets and shoulder items to boost his ilvl stat and get in a better group). The best part of this group was a number of little things that added up to great comedic heights.