"Hitler and Stalin were evil pshycos"
No, no, no. I have a problem with this for cognitive reasons, not because it is factually wrong, but because it is unhelpful when it comes to understanding, how you think about it.
Listing some people as 'evil' and assuming others are good is a gross simplfication, and this hurts how we make decisions about the world; things like terrorism, personal freedom vs security, privacy vs freedom of information...
Good vs evil is a terrible simplification. Was it just Hitler who was evil, what about the guys running his death camps, what about the soldiers in his army, what about the doctors who used bodies from executions to teach anatomy, what about the french who worked with the Nazis? It is all shades of grey, ON BOTH SIDES. There is a moral question over the use of nuclear weapons, i would also ask the moral question of sending boys to die AT ALL, the question of fire bombing civilian cities, there is no 'good' in this story, but there is also no evil.
Also psycho is a medical term, which may be correct, but you are no psychologist!