I think as parents of difficult children we have to evolve a bit. I think with younger kids we put up with more of the verbal junk because we're trying to find answers, strategies, medications, treatment, *anything* that will work. Yes, the MI plays into it - an unstable kid will do unstable things. But, and this is just my opinion, I do think there should come a time when we start drawing lines in the sand. By not responding to the junk, by continuing to let it roll off our backs, I think we are sending a not so subtle message that it's acceptable and okay. I very strongly believe that by early teen years at the latest, we need to at least start more forcefully addressing these behaviors regardless of diagnosis. No one is going to give a darn that thank you's BiPolar (BP) if he goes off the deep end and mouths off to his boss. He will be fired, period. What a shock to him and really how unfair to him if I've allowed the mouth all these years.
I agree with- Mrs. Smith that it needs to be a neutral response to the behaviors (any emotion on my part is just gasoline to thank you's fires) but at the same time there *does* need to be a shift to consequences for and intolerance of the behavior.
Remove the audience. Walk away. Leave the house. Go see a movie or shoot pool or buy a new dress. If he gets an allowance, spend it on yourself because he's just lost his "job" by mouthing off to the boss.
I very strongly feel that it's a huge disservice to potential future functionality if you excuse the behavior because of the illness.