Yes, it’s that time again, for Maastrichts Theory of evil!
Based on god knows how much books I read, I came up with the following statistic on everyday evil. On the whole, I don’t really find “evil” a helpful term when it comes to preventing evil instead of condemning it. It is such an unscientific term. 
In any given situation, your odds of interacting with another person who will act reasonable and kind, is about 85 %. I’m not making that up, that number appears in many studies on how many people will, not try to cheat the system in unstaffed self-checkouts in supermarkets.
Your odds of running into the opposite, an unpleasant person, commonly known as “asshole” is 15 %.
Two-thirds of those 15 % people are the ordinary kind people described above who just have a bad day. They cut you off in traffic, or snark at the telephone because they are themselves stressed, tired, victimized, annoyed, etc. Just like you do when you have such bad days yourself. We are all temporarily assholes to other people.
This is the category where a firm remark: “Stop acting like an asshole”, may help, at least after the asshole has cooled down a bit. It is also the category where changing the circumstances (group standards, chance of being caught) has a large impact.
The last 5 % percent are people who make life consistently difficult for most people around them and for themselves. Many, if not all of those people, have a personality disorder. Some hurt mostly themselves (schizophrenics) and some mostly hurt others (narcissisists, and the 2-to 5 % of us who are sociopaths). This category includes the Sadistic or Narcisstic boss, the (paranoid or obsessive compulsive) Neighbourhood Nut, the criminal, and the Crazy Hobo. You can call them assholes, or evil, but it won’t do you much good besides venting. The only thing that is useful to know is that with them, past results are a good indication of future results.
As for pedophiles, I don’t think you can trot them out as an “always evil”- category. It’s just that they’ve become synonymous with evil in the last twenty years or so, and more in the USA then elsewhere.
A small percentage of people are born with a sexual attraction to little kids; most wil never act on that. IMHO, those that don’t act on it are not evil, and instead deal heroically with one of the shittiest cards life could have dealt them.
As for “ordinary” sexual abuse, when it happens to involve children, and incest, those are complicated enough to warrant a whole library in themselves. Evil (not feeling or acting on, empathy) plays a part, as do psychological disorders, as do some aspects of culture (a sense of sexual entitlement, and large modern mainstream cultural condemnation of such, and the dynamic of dysfunctional families and dysfuntional institutions).
Some people are psychopaths as well as pedophiles and, if the opportunity arises, the worst of the worst may happen.