There are only two film genres whose success you can gauge from the immediate, audible reaction of the audience. A good horror movie can make its audience jump and scream, while a good comedy makes them laugh out loud. If a joke lands and you can hear a pin drop in the theater, you failed. If the monster jumps out and everybody is still in their seats, you failed. When these genres are so difficult to nail on their own, it's amazing that anybody ever makes them work in tandem