I never thought Slenderman was scary until I started watching Marble Hornets.
I think it would be very interesting if Slenderman is involved. It would definitely make for a very creepy house; I can only imagine what it would be like to be walking through a woods, turning a corner, and seeing a twenty foot faceless man reaching at you. I think it would be even scarier though if in every house there was a very small reference to him, like him standing outside of a window in one of the houses, or something.