When those sites list the "types of personalities to avoid", they should just say "stay away from people with personality disorders and other mental problems".
Also just because a person might be unhealthy for one person, doesn't mean they are bad for another person. It has a lot to do with how compatible people are with each other. We all can have some of these traits at any given time, it's just when these traits are severe, or extreme, is when the problems arise. The main thing is, to listen to your gut feeling about people. If they make you miserable, drain you emotionally, or you think there's something about them that isn't quite right, listen to what your instincts are telling you.
Also, Narcissism, or Narcissistic Personality Disorder covers a lot of these toxic personality types.