dirt vs guano

dirt

noun
  • Soil or earth. 

  • A stain or spot (on clothes etc); any foreign substance that worsens appearance. 

  • Previously unknown facts, or the invented "facts", about a person. 

  • Meanness; sordidness. 

  • In placer mining, earth, gravel, etc., before washing. 

  • freckles 

verb
  • To make foul or filthy; soil; befoul; dirty 

guano

noun
  • Dung from a sea bird or from a bat. 

  • Coccothrinax borhidiana, a variety of palm tree indigenous to Cuba. 

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