I like to imagine raids happening in reverse. I like to imagine bosses as very confident, yet not very intelligent, raiders. They keep attacking the guy with the most health and defense. Every now and then, they throw out an ability that targets weaker members, but instead of following up for the quick, easy kill, they keep focusing on the tank. They have tunnel vision, and can't tell when they're standing in fire, and don't know how to deal with people attacking them from behind. And, needless to say, they are terrible with their CD management, blowing their CD's every time they're available, instead of saving them and using them all at once for an easy victory.
I imagine every time they wipe a raid, they get loot from us. It's mostly gold, with a few offspec epics thrown in, or stuff that is a downgrade.
And when a raid finally kills them once, they ragequit and level their alts for a while, but they've calmed down sufficiently by Tuesday to give it another shot.