On evil: most villains in sci-fi/fantasy -- or hell, any genre of fiction, period -- inspire no fear or hate in me.
Take Sauron in Lord of the Rings. Oh, everyone'll cower at the mention of his name. We know he commands a vast army of unwashed, wicked orcs and the spoooky Ringwraiths. We know that, if he wins, he'll cover Arda in eternal darkness. So what? Boo-freaking-hoo. I don't bloody care. Sauron's not threatening. He's just there. He doesn't hurt a character that I can empathize with; he doesn't harm a character that I have come to care about. He just hovers there at the edge of the plot. (Partly, his lack of oomph has to do with the fact that I can't bring myself to give a fig about Tolkien's characters, as I think they are all flat, annoying, and tedious to read about. But again, another separate rant altogether.)
IMO, these vague evil overlords who are evil because, well, the writer tells you they're evil demonstrate sloppy characterization on the writer's part. "Evil" spirits, elemental forces, and suchlike lack character, personality, and therefore they do not give me a sense of menace or intimidation. I prefer my villains to be more personal and much, much more subtle. Perversion of what is considered normal mind, someone who can have tea with you one moment and execute you the next, heartless manipulation -- these are the things that, I think, actually bear some semblance of being frightening.