mare's nest vs train wreck

mare's nest

noun
  • A confused or complicated situation; a muddle. 

  • A great discovery which turns out to be illusory; a hoax. 

train wreck

noun
  • Someone (especially a woman) who is unbalanced and considered a mess, a disaster, one who is suffering personal ruin. 

  • The aftermath of a train crash. 

  • A disaster, especially one which is large in scale and readily seen by public observers. 

verb
  • To ruin utterly and catastrophically, to cause to end in disaster. 

How often have the words mare's nest and train wreck occurred in a corpus of books? (source: Google Ngram Viewer )