I agree it is bloody annoying having to deal with these people, its almost as bloody annoying to keep reporting them too. However, I have been using an auto AFK reporting mod for the last few days and it seems to work pretty well. I no longer have to report anyone I let the mod do it.
I'm sure it is not perfect but it is better than nothing, just pisses me off that blizzard can't do a better sodding job with their own game.
I currently use
TuringTest AFK Reporter | World of Warcraft @ Curse.com here is another that I have used with good results
CattleProd | World of Warcraft @ Curse.com