A pleasing personality of a person enables good interaction with others and also enables the person to achieve a lot. But if personality disorder traits - short temper, aggression, insincerity, cruelty, poor coping skills, poor communicative skills, sadism, etc - are dominating a personality then social interaction is impaired. And that would affect all aspects of personal, interpersonal and social interactions.

Example : Borderline Personality Disorder

Chronic feeling of emptiness, bouts of decreased self-worth, paranoid thinking, easy emotional bruisability, episodes of deliberate self-harm (suicide attempts, cutting oneself, etc) are all seen in such persons. They are emotionally very labile especially with intense personal relationships but otherwise friendly and usually even give good advice to others.