Dirty Mouth

Personally, I am not phased by occasional swearing in a book. In real life, it is not uncommon to hear quite a bit of swearing in casual conversations between friends. If the author wants to replicate this in a book, I have no problem with it. To try to be realistic, sometimes an author must add this. When the author adds it too much though, to the point where it gets to repetitive, it can get annoying.