immoral vs off-color

immoral

adj
  • Breaching principles of natural law, rectitude, or justice, and so inconsistent with the demands of virtue, purity, or "good morals"; not right, not moral. (Compare unethical, illegal.) 

off-color

adj
  • Dirty, vulgar or obscene, especially in a way that is unpleasant. 

  • Feeling mildly unwell. 

  • Different than usual. 

  • Of the wrong color. 

How often have the words immoral and off-color occurred in a corpus of books? (source: Google Ngram Viewer )