A friend of mine read one of my stories recently and told me that the language wasn't very dirty. This surprised me. I thought it was very dirty. When I asked her for examples, she said that the characters could have called each other names.
I've never been too fond of name-calling. It seems mean to me.
My friend said that if the other person wants it, then it isn't mean.
There are a couple moments here and there in my writing where one character might refer to herself as "a slut" or a dominating character will call their submissive a "bitch" but it isn't very pervasive.
I suppose it's possible I could write a story with a little more dirt in my dirty-talk. We shall see. :)