I was taught you should say only good of the dead.
By way of Lawrence, I have learned that General Vo Nguyen Giap, described by the NYT as “the relentless and charismatic North Vietnamese general whose campaigns drove both France and the United States out of Vietnam”, has died.
(I’ll have to go back and look: did the NYT ever describe Hermann Göring or Erwin Rommel as “relentless and charismatic”?)