Well, PZ's weighed in on the corruption of Scooby-Doo, and I followed some links from there. Whenever I get off on a rant, my regular readers know there's a fair chance of me mentioning the "Hollywood skeptic" stereotype: The denialist who disbelieves in the monster right up until it eats him. In the conversion narrative Hollywood is fond of, the depressed skeptic doesn't believe right up until the monster almost eats him, survives to the happy ending, and somehow becomes magically happier as a result of becoming a woo.
I've never been much of a horror fan, but it does seem to happen a lot there. Either the skeptic gets eaten, so all the woos can cheer at his foolish demise, or he gets converted, so that the woos can feel inspired to go out and evangelize to us skeptics, showing us that we can believe in "something more" (a phrase that merits a doggerel entry, coming soon).
One problem I see with having a skeptic in a world that features supernatural stuff is that he's usually an exaggerated version of skeptics from the real world. In a supernatural world, I would think skeptics, and by extension, the events in such horror films, would be more like Ghostbusters: If supernatural things existed, we would have studied them in detail and devised countermeasures. If something has effects, it can be studied scientifically, "supernatural" or not. There'd be no way to keep this stuff secret, since that'd require massive cover ups with outrageous administrative costs. About the only scenario I can think of that would result otherwise would be if the supernatural was very rare, or if the horror movie was the result of the first supernatural event anyone was around to care about. No doubt this'll get sorted out in some of the comments.
Anyway, one thing you almost never see in Hollywood is the reverse conversion: from woo to skeptic. I guess it's just not all that ratings-friendly.
But that won't stop me from trying to come up with one:
Setting: Samurai and Ninjaful Japan, inside a key fortification currently under siege. After the assassination of some high-ranking officers and sabotage performed by the enemy's ninjas, morale is low, and supplies are running short. Thankfully, allies manage to squeeze past the besieging army and bring in vital supplies, reinforcements, and most importantly, a renowned general known for his practicality and success on the battlefield: A skeptic.
The remaining officers begin briefing the general on what's been going on, to tell him what sort of supernatural horrors to expect when his assassination attempt comes, and bring in guards who encountered the ninjas who begin to tell their stories, complete with wire-fu flashbacks.
Flashback #1: Guard describes encountering a ninja with a long black scarf and tassels hanging from the handles of his kunai knives after assassinating one of the officers in a poorly lit hallway. The ninja starts attacking the guard, seeming to jump around, magically attacking from multiple angles, forcing the guard to remain on the defensive until the footsteps of more guards coming encourages him to escape, leaving a bewildered and demoralized guard behind. The arriving soldiers come in time to see the ninja turning a corner into an unlit hallway and seeming to melt into the darkness. They pursue and see only a long, empty hall.
Flashback #2: A ninja wearing a cloak drops from a ceiling onto an officer and his guards. He manages to kill his target during the surprise attack and quickly jumps away to avoid getting surrounded. He manages to parry a few blows from the guards, swings his cloak around, and in a puff of smoke, turns into a vicious wolf who charges the surprised guards. Flash forward: They show the general the dead wolf body and move to the next flashback, delivered by an injured officer who just barely managed to survive.
Flashback #3: Another officer being escorted by guards, turning past a noblewoman toward a dark hall. A sound comes from the distance, causing the guards to rush to the front and hold up their lanterns to light the darkness. As they do, a shadow rushes past them, followed by the noblewoman screaming: The officer has a knife in his back and he falls over.
Flash forward: The general looks grimly, and points to a scar on his neck, "If I had believed stories like that, the ninja who once attacked me may have been able to finish his job on the second attempt. Ninja are masters of deception, not sorcery."
Revised Flashback #1: The ninja with the scarf and tassels doesn't teleport around the guard to attack from multiple angles. Instead, he waves the various objects in front of the guard's eyes in time with his movement. (Flash forward) "This technique is called (insert cool-sounding Japanese phrase). If he could move as you describe, why are you still alive? He wasn't trying to kill you..." (flashback) "...he was buying time for his allies." While the guard is being distracted, two other ninjas rush out, one even briefly aiding the attack to make the 'jump around' effect more convincing. The two hidden ninja manage to escape, followed shortly by the third after the extra guards start becoming audible. When they see him turn the corner and look down the dark hall, the camera pans up to show the ninja hiding in the rafters.
Revised Flashback #2: Shown from behind the ninja, he throws his cloak around, obscuring himself from the guards as he throws down a smoke bomb. He pulls out a dog whistle as he runs into the smoke, and in comes the wolf, attacking the guards while the ninja escapes.
Flashforward plus an anachronism: The general asks to see the knife that went into the surviving officer's back and dusts it for fingerprints, finding two sets. He checks the guard who pulled it out to match one. He asks for them to bring in the noblewoman, who comes in and describes a ninja forming out of the shadows. The general has her fingerprints checked: They match the other set. (flashback) The noblewoman generates the noise by throwing something down the hall, causing the jumpy guards to look ahead. Their swinging lanterns generate flowing patterns of light and shadow. While they're distracted, the noblewoman plunges a knife into the officer's back. Include slow-mo scene of the officer's face as he realizes something is wrong and begins falling. The noblewoman steps back to her original position and screams at the top of her lungs.
Wrap-up: The general figures out that the noblewoman was acting as a spy, coordinating with other ninjas. General manages to foil an assassination attempt to the point of utterly embarrassing the ninja through appropriate planning, including good lighting everywhere. (Insert 'candle in the darkness' symbolism) Troop morale rises as they realize they aren't dealing with an unstoppable supernatural threat, and as a result, they are able to last through the siege until outside forces arrive.