How about words that are only common in the negative?
Nonplussed
Disheveled
Ruthless (I got Eeees on this one once while playing Scrabble. We play a cutthroat game where challenge-losers forfeit a turn. One time, I played “ruth” which earned me a challenge. I figured that if you can be ruthless, you can have ruth. Sure enough, it was in the Scrabble Dictionary and she lost a turn.)
The Wolf