I think a person can use all kinds of "bad language" and still be a very good and moral person...
...the defining line is where the language is used without any regard for context and environment.
For example: I have a friend we'll call Cursing Guy, who curses quite a lot. A fucking shitload, in fact.
I would consider Cursing Guy a very moral and upstanding person apart from that. His absolute saving grace is that, despite his prolific cursing/other bad language, he knows when is not the right time to use those words and terms, and adjusts his speech accordingly. When in mixed company where certain things would be inappropriate if said aloud for all to hear, he does not say them.
For myself, I can curse and use bad language with the best of them- but never in an inappropriate setting, or in a way that would offend people within earshot. I am extremely mindful of what I'm saying and around whom I'm saying it.
There are some times when you simply can't accomodate or anticipate the moral standings or threshold of a person in your company or within earshot of you. The best any person can do is speak their mind honestly. If you are true in your words, it will be difficult for someone to be truly offended on a real level when you explain your position.
This is not to count, say, if the "offensive" quality is simply a matter of opposing opinions on a matter- I've had people tell me that it was "offensive" of me to say I dislike children and that they were a waste of quality time and money that could be spent with/on an SO. Well it's obviously not "offensive", it was just their expression of disapproval of my opinion.