Scary does not have to mean bloody
I'm greatly looking forward to seeing "The Conjuring," as a horror-movie buff who particularly appreciates the fine art of telling a scary story without excessive gory violence. I'm not a snob about that - two of the three films in my all-time great list of scary movies, "Jaws" and "Alien," have plenty of bloodshed, although neither of those films are really vulgar about it. (The mess hall scene in "Alien" gets a special exemption in my book, as one of the rare cinematic moments that was truly unprecedented, and will never be duplicated.)
But the scariest film of all time, "The Exorcist," has a body count of three: one ambiguous murder we don't even see, one heart attack, and one demon-stomping act of noble sacrifice. The hugely successful "Paranormal Activity" films don't get ugly until the very end, and their violent final scenes are quite muted by modern standards - you'll see plenty of network TV shows with more graphic violence. Also, the "Paranormal" films get all the goosebump heavy lifting done long before they turn feral. I never thought I'd see an entire theater leap out of its seats because a bunch of kitchen cabinet doors slammed shut.
The director of "The Conjuring" gave us the bloody "Saw" films, to be sure, but he was far more unsettling when he left the buckets of blood behind and made "Insidious." I'd also mention "The Blair Witch Project," which has picked up plenty of detractors over the years, and the shaky-cam ruins it for many viewers, but I think the film buried under all the hype stands up well as a spooky movie that doesn't spill any blood.
I admire the creativity, character work, and atmospheric craft necessary to make something truly scary without bloody violence. It looks like "The Conjuring" fills that bill. Anyone interested in a really outstanding example of the form should look up the George C. Scott film "The Changeling," an under-appreciated grand-master class in using character, setting, and elegant creepiness to scare the crumbs out of an audience without a drop of blood. I'll see your slasher-film meat cleavers and chainsaws, and raise you a cobwebbed wheelchair and a bouncing rubber ball.