Psychopaths can be very charming.
Antisocial personality disorder is characterized by a long-standing pattern of a disregard for other peoples rights, often crossing the line and violating those rights. It usually begins in childhood or as a teen and continues into their adult lives.
Antisocial personality disorder is often referred to as psychopathy or sociopathy in popular culture. However, neither psychopathy nor sociopathy are recognized professional labels used for diagnosis.
Individuals with Antisocial Personality Disorder frequently lack empathy and tend to be callous, cynical, and contemptuous of the feelings, rights, and sufferings of others. They may have an inflated and arrogant self-appraisal (e.g., feel that ordinary work is beneath them or lack a realistic concern about their current problems or their future) and may be excessively opinionated, self-assured, or cocky. They may display a
glib, superficial charm and can be quite voluble and verbally facile (e.g., using technical terms or jargon that might impress someone who is unfamiliar with the topic).
Lack of empathy, inflated self-appraisal, and superficial charm are features that have been commonly included in traditional conceptions of psychopathy and may be particularly distinguishing of Antisocial Personality Disorder in prison or forensic settings where criminal, delinquent, or aggressive acts are likely to be nonspecific. These individuals may also be irresponsible and exploitative in their sexual relationships.
A personality disorder is an enduring pattern of inner experience and behavior that deviates from the norm of the individuals culture. The pattern is seen in two or more of the following areas: cognition; affect; interpersonal functioning; or impulse control. The enduring pattern is inflexible and pervasive across a broad range of personal and social situations. It typically leads to significant distress or impairment in social, work or other areas of functioning. The pattern is stable and of long duration, and its onset can be traced back to early adulthood or adolescence.
http://psychcentral.com/disorders/antisocial-personality-disorder-symptoms/