For me, cleaning up my language has been a work in progress. Having left my faith in my younger years, I picked up some very ugly habits that I truly wish I hadn't. I am horribly guilty of slipping, now and again. When I do, I hear it from my teens, but I think they would agree I am improving still, although not perfect.
As our children have gotten older, we've had to battle the influence of their friends and the words their friends are allowed to use. We felt it was important to draw a distinct line between what we feel is appropriate language usage and what was inappropriate, regardless of what their friends said. As far as we know, our teens have respected our standards, at least in our hearing.
I have a wonderful friend whose definition of vile cursing is completely different from my definition of vile cursing. I'm amazed at how she was able to maintain such a high standard in her home. All three of her children are teens and absolutely will not use the words "stupid", "dumb", "butt", "suck" (as in that totally sucks!), or "hate". Quite honestly, I admire her for having such high standards. I've been embarrassed on occasion and have had to apologize for one of my own children (Lil' Wingnut) using "curse" words in front of this family.
I suppose what I'm getting at, in this somewhat meandering post, is that we need to have standards in our families. We also need to recognize that other families may have different expectations than ours and that we need to be sensitive (within reason) to one family's ideals while being tolerant (within reason) of another family's apparently lower standards.