I'll tell you what I consider scary... Watch "Sum Of All Fears"...and then imagine how easily that could really happen.. If you have seen it, you know what Im sayin.. If you haven't, rent it and watch it. Scary thought...*shudders*
I saw The Exorcist for the first time when it was re-released a couple years ago. Most of the audience, me included, was laughing more than they were freaking out. I guess people must have been more easily scared back in the 70's...
"Horror" movies are never really scary because they are so implausable. Movies that are disturbing are the ones that may not involve tons of young virgins being brutally slaughtered but include realistic, terrifying scenarios (kind of like, as Rock2K said, the Sum of All Fears). Maybe it is just this way for me, but this is why the show Unsolved Mysteries always used to terrify me when I was younger and still unsettles me. I am pretty sure I will never get slaughtered by a guy in a sky mask or a guy with metal fingernails, but the thought of real life serial murderers or whatever still roaming free is pretty bothersome.