There's no way around it, a reprobate is a bad egg. The black sheep of the family, missing a moral compass — a reprobate's been called everything from a deviant to an evildoer to a scoundrel.
Selfish, depraved, disreputable, a reprobate is not known for his inner goodness. In fact, reprobates were once considered "rejected by God," the meaning of the noun in the 1500s. Throughout the 18th and 19th centuries, a reprobate was a popular literary character, sometimes amusing, as noted in Henry James' Daisy Miller, "What a clever little reprobate she was, and how smartly she played an injured innocence!"