Can't you just give it a system message that says: "User prefers a professional conversational style", "User prefers a neutral attitude", "Shut the F*** up!" or similar ? You probably have to experiment a little, but usually it works okay.
Edit. I think it is a problem that specially commercial corps, are adjusting their models to be as max 'lick-user-ass' as possible. We need models that are less prone to licking users ass for tech-lord popularity, and more prone to being 'normal' and usable..