Perhaps you saw this essay called "Creep Show," written by Kevin Keck, about a six-year-old who is fascinated by zombies, Freddy Krueger and assorted other horror-rific things. (You'd remember if you saw it; it's the essay accompanied by the image of a kid who looks a hell of a lot like Robert Smith from The Cure.) 
Keck writes about his stepson Gavyn's obsessions with an appropriate mixture of acceptance and concern. He knows his boy is a gentle, good kid. But he also wants to shield him from some of the scarier movies and TV shows in which Gavyn has a keen interest. He's allowed to watch "Shaun of the Dead" and even "Scream," but not, under any circumstances, "Saw." All of which raises a question that strikes me as particularly pertinent at Halloween: How do we know when we're exposing our kids to something too frightening for them to handle?
I have seen examples at both ends of the "freaking out the kids" spectrum. On the exposing-them-to-too-much side, I once sat in a movie theater behind parents who brought their five-year-old daughter to see "Saving Private Ryan." The pigtailed little girl was curled up into a trembling, petrified ball after 30 seconds of the opening battle scene at Normandy, and I don't blame her. It was too intense for most of the adults in the multiplex, let alone a child. And in that case, mom and dad didn't have the luxury of saying, "It's just a movie." War is real and even the film version of it is no place for a kindergartner to visit.
But I also think it's equally dangerous to be overly protective, too. I know parents who wouldn't let their kids read books like "Where the Wild Things Are," even when their sons and daughters were of elementary school age, because they thought such stories would scare them. Obviously we don't want to terrorize the little ones, but assuming they can't handle anything even vaguely dark also shields them from some of the most wonderful, imaginative movies and books ever created. Other parents won't even take kids trick-or-treating out of fear of potential fear. And that seems sad to me, too.
Ultimately, Moms and Dads know their children better than anyone and, in theory anyway, should know what's best for them. In most cases, I believe they do. At the same time, I think there are things we can all agree on.
1. You shouldn't take a kid to see "Saving Private Ryan" or "Saw."
2. It's OK to see "The Wizard of Oz" prior to the age of 16.
3. Even scary movies, stories or moments can immediately seem less terrifying if mom and dad are present and talking to their children about what they are seeing.
Keck pointed out that he doesn't let Gavyn watch anything creepy by himself. So while I might not let my own six-year-old see "Scream," I can tell that Keck is trying to be a responsible parent and look for cues from his child about what's too much. Sometimes that's the best and only thing one can do, especially when your son really, really wants to grow up to be a zombie slayer.