clean as a hound's tooth vs unstudied

clean as a hound's tooth

adj

  • Very clean; very innocent. 

unstudied

adj

  • Free of artifice or cunning; innocent, spontaneous and unaffected. 

  • Not gained by study. 

  • Not studied. 

How often have the words clean as a hound's tooth and unstudied occurred in a corpus of books? (source: Google Ngram Viewer )