...you're doing a collection quest and you don't understand why the widgets aren't dropping -- until you realize you're grinding in the wrong area?
And doncha hate it when you're just a few pulls away from finishing an instance when your main tank says, "Sorry guys, I've got to go, I didn't realize it was so late"?
And doncha hate it when you finally grab that last pig's spleen, turn around to head back to the quest hub -- and walk right into an elite who sends you back for a corpse run?
And doncha hate it when you go to turn in a quest after leaving an instance run... and then realize you left the quest item back on the last boss' corpse?
I mean doncha? What else do you hate in game?