ghostwriter vs ink slinger

ghostwriter

noun
  • A professional writer who is paid to write material that is officially credited to another person; one who writes on behalf of someone else, often for a celebrity. 

  • Smith was listed as the author of his autobiography, but a ghostwriter did most of the work. 

ink slinger

noun
  • A writer, especially of low-quality writing. 

  • A tattooist. 

How often have the words ghostwriter and ink slinger occurred in a corpus of books? (source: Google Ngram Viewer )