prettify vs put lipstick on a pig

prettify

verb
  • To make pretty or prettier, to make more attractive, especially only in a superficial way. 

  • Synonym of pretty-print 

put lipstick on a pig

verb
  • To superficially alter something in the hope of making it seem more appealing than it is in actuality. 

How often have the words prettify and put lipstick on a pig occurred in a corpus of books? (source: Google Ngram Viewer )