Give The Devil His Due Meaning

(idiomatic) To acknowledge the positive qualities of a person who is unpleasant or disliked.

Example: 1597, William Shakespeare, King Henry IV, Part I, act 1, sc. 2:
  . . . for he was never yet a breaker of
  proverbs: he will give the devil his due.
1821, Sir Walter Scott, Kenilworth, ch. 4:
  Yet give the devil his due; Says grace before he doth a deed of villainy.
1922, Zane Grey, The Day of the Beast, ch. 5:
  And to give the devil his due he's finer than ever. Too damn fine for this crowd!
2007 April 5, Richard Schickel, "The Fog of War Resistance" (film review), Time:
  We are obliged, at least this once, to give the devil his due — and to consider the possibility that he may even be, in this instance, the angel of bleak truthfulness.