HoJ+Exo-Spam. I once met a Paladin who HoJ'd me. He had /spit and /rofl binded to his Exorcism... So It was HoJ+Emote Exo-Spam. >.< And he was spamming Exo during the cast time too. Freaking busted my balls. I facepalmed so hard.
People raging at my P2P Disc priest in non-twink BGs. "Dude, learn to heal!" "I'm DPSing." "You suck, you're a priest!" "Hey, atleast I'm bubbling FC and bubbling the rogue and pally going after EFC!" I got into that exact arguement, and so the guy replied "Lol we could use you at the enemy GY to farm, nub."
Feral Druids who don't use thorns. Thorns + Mangle Spam is an incredibly OP combination, and pretty obvious.
Rogues who make the enemy aware that he is with them. I met a rogue who followed the EFC and sapped everyone, and /spitted and /danced, etc. I face palmed so hard.
Hunters claiming that skill is based off of who gets the most KBs, and damage. These hunters are usually the backpeddlars who sit in the middle or at the enemy GY, and often will call the people going after EFC, people FCing, people assisting FCers bad, since usually, the people focusing on the objectives don't get too much KBs or damage. These hunters also tend to blame people for not going after EFC and not helping FC if his team loses, even though he doesn't do that stuff himself. Of course, though, these hunters are the baddies who want a big epeen. The good hunters are the ones going after objectives.
And... People who take this game WAY too seriously, often screaming at people who suck or screaming at people who aren't playing at their best. They treat the game as if it should be a priority, and will never help the 'redeemable' newbies, and claim anyone who costs the game is the worst player ever. I am a competitive player, but when people start swearing and name calling, I tell them it is just a game, and these players are like "And you suck at it!" That is the biggest face palm ever. People who treat this game as if it is their life, and if they die, it is the biggest pain ever.