Dirty Mouth

The obscene language is critical to every part of the book. It helps really illustrate the state the characters are in. Its just another way to show how they feel through dialog. If the author was trying to show the characters are in duress and are angry through characterization and symbols but had them talking politely or without obscene language it wouldn't make sense. Obscene language is a reality and it exists for a reason, so if it is real it must also exist in books to make them real.