To be ultra technical, true Psychopathic characters (not ones like ">8C I CLAWD UR FACE OFF BECOZ I'M A PSYCHO") do not particularly have any "reason" to be "evil". They pretty much kill/hurt/manipulate others "for the lulz"
"Researcher Robert Hare, whose Hare Psychopathy Checklist is widely used, describes psychopaths as "intraspecies predators".[19] Also R.I. Simon uses the word predator to describe psychopaths.[20] Elsewhere Hare and others write that psychopaths "use charisma, manipulation, intimidation, sexual intercourse and violence"[21][22][23][verification needed] to control others and to satisfy their own needs. Hare states that: "Lacking in conscience and empathy, they take what they want and do as they please, violating social norms and expectations without guilt or remorse".[24] He previously stated that: "What is missing, in other words, are the very qualities that allow a human being to live in social harmony".[25]" Wikapedia'd.
I think it'd take some skill to properly rp a Psychopath, since most people seem to overlook the key fact that they, under no circumstances, will randomly fall in love or be like "I'M CRAZY NO ONE LOVES ME". Or even care about others. Even if they care about one single being, it removes the Psychopathic trait.
Not to mention all the other traits that come with Psychopathy.
|D I think I'm looking into this too much.
BUT YES I do agree that those who are "nooby evil" and act "evil" without a set reason and aren't rped well are obnoxious.