 The unexpected signs that someone might be a psychopath don't work common than you think. A study shows that there's a tendency for people who have psychopathic personality traits to prefer black coffee in other bitter tastes. People with psychopathic traits have a hard time differentiating between smells because they typically have lower functioning frontal parts of their brains. Psychopaths like to keep connections to their exes because it allows for an opening to their resources.