brighten vs put lipstick on a pig

brighten

verb
  • To make illustrious, or more distinguished; to add luster or splendor to 

  • To make more cheerful and pleasant; to enliven 

  • To grow bright, or more bright in color; to clear up 

  • To make bright or brighter in color. 

  • To become brighter or more cheerful in mood 

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 brighten and put lipstick on a pig occurred in a corpus of books? (source: Google Ngram Viewer )