Scientists from the University Innsbruck have studied the relationship between personality traits and the tendency to specific flavors. They found that people who like bitter foods/beverages are more prone to narcissism, sadism, Machiavellianism and anti-social behavior.
Hundreds of Americans who have been exposed to various categories of tastes (sweet, salty, sour bitter) were chosen to be volunteers. They then were rated according to the preferences and respond to personality test questions. The results of the study showed that people who indulge in bitter foods and drinks show signs of psychopathic or psycho-deviant behavior. These people are also often self-loving and extremely selfish. The tendency toward bitter taste in humans indicates their need to expose themselves to danger, and they require strong thrills.
The more the person was kind and ready for collaboration, the less he/she had the need for bitter tastes.
The conclusion from this study is that people who drink bitter coffee without milk and sugar and love dark chocolate may be psychopaths.