bunco-steerer vs smooth operator

bunco-steerer

noun
  • A swindler; a cheat or con-man. 

smooth operator

noun
  • A skillful, manipulative person, con artist, or clever scoundrel. 

  • A person who accomplishes tasks with efficiency and grace, especially one with verbal skills who is persuasive in interpersonal relationships, negotiation, etc. 

How often have the words bunco-steerer and smooth operator occurred in a corpus of books? (source: Google Ngram Viewer )