filth vs stag film

filth

noun
  • Smut; that which sullies or defiles the moral character; corruption; pollution. 

  • The police. 

  • Dirt; foul matter; that which soils or defiles. 

  • A vile or disgusting person. 

stag film

noun
  • A kind of pornographic film produced clandestinely in the early to mid-20th century, typically short and without sound. Usually intended for a male audience. 

How often have the words filth and stag film occurred in a corpus of books? (source: Google Ngram Viewer )