I think they actually can. Psychopaths usually try to fit with society, so when someone or something doesn’t interact badly with their plan, they tend to be neutral or polite.

But it’s a good question

I'm gonna guess it's possible but rare given that pscyhos and socios tend to use facades.

Well, Kimblee is example of psychopath and affably evil. He isn't nice, but he sophisticated, honest and noble. Mario from SMG4 are too good example. He isn't actually "bad man", but his psychopathy are real pain in neck, believe for me, I know him -_-

Psychopaths can have fondness for other people and moral codes, even if they have an lack of empathy, making them possibly affably evil.

I think that the morally gray psychopathic characters are usually affably evil as well.