Mack Sennett must have had an easy time sleeping. Coming to work wasn't much of a challenge since all he had to do was had his actors react. The situations didn't have to be clever, indeed better if they aren't. Its a strange brand of humor, very temporal.
The idea in this case as always is that you have simple character types that we can recognize in seconds. They encounter a situation that allows them to make faces, act ridiculous and indulge in some physical humor. We know from the title that this will be fake ghosts.
The humor depends on the cheap nature of the threat because we know we wouldn't be "fooled" a moment. So part of the humor is watching our young woman scream and run, and part knowing that such a person exists.
Ted's Evaluation -- 1 of 3: You can find something better to do with this part of your life.