So I was messing around, creating new worlds with seeds yesterday, and tried using a few "bad" words as seeds. Not naughty words, mind you, but words like "hell" and "cruel" and "creeper." I wasn't having much luck, not even the map with "Herobrine" as the seed seemed to do much, but I think I may have found something with a seed of "evil." I typed it in, loaded up the world. Nothing seemed different, but the landscape was kind of neat, so I decided to explore. Nightfall, made a quick base. Daytime... leave my base. There were probably 10-15 creepers waiting around my front door. Coincidence? I'm not so sure.
Taming Spiders!
My Suggestions on Goblin Villages