clean language vs obscenity

clean language

noun
  • A questioning technique focused on the use of language, assumptions, metaphors, paradigms and sensations familiar to the person questioned. 

obscenity

noun
  • Specifically, an offensive word; a profanity; a dirty word. 

  • An act of obscene behaviour. 

  • The qualities that make something obscene; lewdness, indecency, or offensive behaviour. 

  • Something that is obscene. 

How often have the words clean language and obscenity occurred in a corpus of books? (source: Google Ngram Viewer )