The bad guys I've known were could be very charming when it mattered or to the right people. It took several months (sometimes a year) for people to compare notes and realize they were basically jerks. One of the nicest guys I've ever met I later found out verbally abused (and sometimes physically abused) his wife, often stole money from her purse to go get high, left his kids in a seedy part of town because he was too high to remember where they were, and spread many horrible, demonstrably false rumors when they separated. Maybe some of the people you helped because you thought they were nice, many years from now, you will realized they are sociopaths.