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.

Bryce Walker is a physcopath but arguably (repeat arguably) affably evil. He definitely is affably evil in season 3.

No. Psychopaths don’t feel empathy or remorse and are generally emotionally detached from other people. They may make friends in order to blend in with society, but that’s all their “friends” are: a means to an end. They may occasionally develop obsessions or some form of attachment (i.e. Kilgrave with Jessica Jones and Homelander with Madelyn Stillwell), but it’s not genuine care (in both those examples the psycho/sociopath ends up trying to kill the other person). They may be neutral towards normal people, but that’s not really genuine politeness per se, it’s just... nothing.

And Bryce Walker isn’t a psychopath. Kind of. See, in the first two seasons, Bryce was an actual diagnosable psychopath who felt either nothing, lust, or hatred towards everyone around him. But thanks to the show’s awful writing, he randomly developed a conscience in season 3, and was just no longer a psychopath (which isn’t how it works IRL, psychos and socios can’t be cured), hence why he’s no longer in the category. I really hate 13 Reasons Why.

I mean the show sucks but he ddI show sings of redeeming qualities in the first two season. He stopped Monty from beating up Tyler in season one and even offered Clay a towel after beating him down to the ground. But yeah most of his redeeming qualities and especially remorse really did come out of nowhere.