drawback vs worm in the apple

drawback

noun
  • A disadvantage; something that detracts or takes away. 

  • The inhalation of a lungful of smoke from a cigarette. 

  • A partial refund of an import fee, as when goods are re-exported from the country that collected the fee. 

worm in the apple

noun
  • A serious flaw in something otherwise good; a problem that ruins everything else. 

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