I don't really think it can. I think evil is worse when a smile is its cover. This is so, in my opinion, because real rotteness, honest to goodness (?) horrifying evil, is impossible to hide. It is detectable in so many ways. When it slips into a disguise it fails.
This is one-to-one evil I'm talking about. Personal and in the room with you. The stuff of horror films and books!
I've encountered evil along the way and shrugged it off, but sometimes, it's so potent, so in your face, it can't be ignored. If that ever happens and you're a writer or artist--observe it! Analyze it for future reference. Let its horrific image stay with you so you can use it creatively. Whatever you do, know evil for what it is, because when you do, you take its power.
All writers do is observe, we have a great big world in which to learn so much! And everything learned, becomes a library from which we can draw resources!