I would think that after facing so much gory and scary stuff in their daily work, they would have watched something more lighthearted....like Charlie Chaplin, you know. A good time out and away from dealing with serial killers isn't going to the movies to watch serial killers. That's my opinion, really.

Maybe they are just using it as an opportunity to warm-up their profiling skills. Or laugh at the special effects.

Or maybe they take comfort in the fact that the unsubs....I mean, villains in many B-grade slasher movies are more predictable and clichéd than your average murdering plank of wood.

Girl sees knife/chainsaw/cleaver/axe/pitchfork/spoon. Girl screams. Girl dies. Stab, stab. Who cares, the girl is only murder fodder and possesses the characterization of a matchstick.