Meh.. Evil doesn't exist... Only within human context.
Animals kill each other, but that neither evil or good. It's just life.
Our brains just complicate things I guess
Those terrorist Muslims think they are doing good by cleansing the world of anything opposing Islam. Same goes for christians who have been indoctrinated since birth. On the other hand we think we are doing good when we try to de-convert Christians, yet some Christians call this the work of the devil.
So yea.. What is truly evil, I don't know. It's incredibly subjective. I don't find sadism evil at all, unless that person hurts someone who did not consent to it.
Personally, I think acting malicious is evil. There is no excuse for maliciousness. There is no excuse for wanting to put others down in order to gain from it... And usually people do it for popularity, or some other stupid thing.
For example, I find those 'Anonymous' idiots to be evil.. Not all of them, but most of them. They maliciously join lets-ruin-someone's-life-bandwagons and they know this. They are 100% aware that they are hurting someone out there. And yea, you may say that "Internet is serious business"... But I'm not talking about normal online bullying.. More the kind where they expose their personal info and send death threats. I find it outright scary that anyone has the urge to do this.
But all in all... It doesn't really matter... If you put "outside view"-goggles on, free of any human thought, you'd realize there's no evil... Just matter... And matter interacting with matter. In the end, we have a big bang, stars, planets, and maybe the end of the universe somewhere in the future.
Well those are just my thoughts.
Edit: Man.. Now Im depressed <.<