muckrake vs tarnish

muckrake

noun
  • A rake for scraping up dung. 

verb
  • To search for and expose corruption or scandal, especially as a form of investigative journalism. 

tarnish

verb
  • To compromise, damage, soil, or sully. 

  • To lose its lustre or attraction; to become dull. 

  • To oxidize or discolor due to oxidation. 

noun
  • Oxidation or discoloration, especially of a decorative metal exposed to air. 

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