maintain vs palm off

maintain

verb
  • To declare or affirm (a clause) to be true; to assert. 

  • To keep up; to preserve; to uphold (a state, condition etc.). 

palm off

verb
  • To sell or dispose of (something) with the intent to deceive; to attempt to pass off a counterfeit or inferior product as genuine. 

How often have the words maintain and palm off occurred in a corpus of books? (source: Google Ngram Viewer )