In my experience, black cats are either extremely sweet and loving or totally crazy and wild. I've seen a lot more of them who have been sweet and loving than the other, so I believe that they all would probably be that way if they were not mistreated by someone, especially those who are superstitious.
My son has a black male and his tortoiseshell sister who will turn 1 yr old next month. Our family adopted a black queen in 1994 and she blessed us with 4 black kittens and 1 white (Siamese) kitten on July 4th that year. Her daughter lived the shortest time--she had a heart attack early one morning. The mother and the males all lived close to or longer than 10 years and might still be alive if not for the cancer each one developed. We loved them all and they loved us, so we were blessed to have them for as long as we did. Their memories will live on in our hearts, so they are still with us, in a way.