)I don't think YOU are dumb, I just think that there are a lot of dumb hunters out there. If played well, the class is amazingly fun and deep and wonderful to have in a group. But there are some skills that are vital for late game grouping that hunters just never have occasion to develop because, for the most part, soloing never tests them. How good are you at keeping mobs trapped away from the group? Kiting mobs away from healers? Effectively pulling an instance with MD? (Pulling is a subtle art, and hunters really are made for it, but you rarely see a hunter good enough to do it.
If I was in a regular shadowlabs with you, and I knew it was one of your first late game dungeons, I would be happy to help you learn some of these things. I know it can be exhausting to listen to us talk about all this stuff that is kind of over your head at this point. But sometimes, when you reach a certain level of play (raids and higher end heroics) we take for granted that there are certain things people are able to do. A warlock is able to use up to 3 forms of CC at once, mages are able to keep close watch on their polymorphs and aoe without getting crushed, a warrior is able to effectively build aggro and protect the healers from getting it, a healer is able to keep alive under pressure and dole out heals where they are needed to prevent a wipe, rogues need to stay in melee range, and be quick with stuns and interrupts. Hunters need to pull effectively and use their survivability to protect the more fragile members.
But like I said, 5 man dynamics is something that takes practice. That's why the standard dungeons exist, they provide a great learning curve for raids and heroics. Players who get past that learning curve without learning basic class mechanics can annoy those of us who do understand our class.
i'm PRICKLY!!)
i love you guys!! 
