I dont AFK-bot, but my guildi talks alot in the start. In AV he says he can sneak inside the mines (NPC opponents) so that ppl have to kill their way trough the mobs just to see what he is doing. When ever he checkes on his char to see if he is dead, he says a joke or something that give ppl "the happy feeling"
Sounds very logical to me.
Oh... and never ever use a afkbot that uses wow in any way. Only use the auto-keystroke IMO.