We haven't run in to word issues often yet. The only one I recall was the "n" word in an early Hardy Boy book. He somehow skipped it (he has vision issues and sometimes skips words or lines)and I tried not to stare or look too shocked. It really took me by surprise.
Generally though like Ametrine said I take it as a teaching moment... "he/she isn't talking very nice" or what do you think (character B) felt like when (character A) said that? He knows about strong words and hyperbole so it isn't hard to have a healthy discussion. At 6, he self edits pretty well and turns off TV or books that get inappropriate. I don't really expect that to last though.
