I know someone who I believe to be anhedonic, but I also think it has gone past that to a psychosis. This person only seems to enjoy hearing of others in dire straits. There is no steady mood from one moment to the next. Offensive and abusive language and acts of violence are very commonplace.
Situations are always described with little or no basis in the reality and always with an extremely dark overtone. It certainly seems to be more than anhedonia to me.