Gym, it would have to depend upon the context. Most Haunted Attractions are the run of the mill, variation on the same things. The Raven's Grin Inn (On my bucket list to visit) would be another story, so you have an advantage there. There is nothing run of the mill about your place, and that's a good thing!
The big thing is, that in an attraction I paid to go to, I am expecting to be scared. Having something happen that looks like it is not supposed to happen, would scare me, or at least put me out of my comfort zone.
At an attraction or at home? At home, I've got a long list... the giant unexpected spider or snake, window creeper, midnight burglar, etc. With all of those, after the initial shock, I would attempt to dispatch the offending critter with extreme prejudice.
At an attraction? I've never seen this done... but I think an awesome scare would be to have a clear Lexan floor that would mimic a sheer drop-off or a floor give-out in a narrow hallway. The lights (in the hole) would come on at just the right moment to reveal the floor directly in front of me appeared to be missing. Even if I knew it was a gag- I know I would jump back from the edge.
The first time I was looking at a computer's screen I asked the local Librarian what buttons to push in a search (I guess? ) for my name.
It brought up an on-going discussion where the question was asked :"Does anyone know how to instill real fear of physical pain without using a chainsaw?"
The answer was "Jim Warfield" @ Ravens Grin -mount Carroll, ill.
Numerous total strangers to me were , talking about me. (I must have scared or impressed .. someone?) (insert evil laugh here~~~)
It depends on what kind of scare we are talking about. If we are talking the classic jump-scare, I am fairly easily startled, especially if I am thinking about a lot of things at once and something pops out at me. To truly scare me, it would take a lot. Horror movies and ghost stories don't bother me, not even the real-life paranormal shows with people telling what happened to them in a seemingly ordinary home. To be honest, heights scare me more than anything else.
Even though Illinois is known to be pretty "Flat", where I live is the hilly portion of this state. A drive North and West of here, cross-country over blacktop roads offers stunning panoramic views of long distances of valleys stretching out forever, which could end up at the very high cliff overlooking the Mississippi River. "look down from that cliff , the highway below seems to be inhabited by cars all made in the "Matchbox" car company!"
Looking slightly up there will be that big river with islands and sand bars, trees, a very wide expanse, but just ten miles downstream IS the widest part of the entire Mississippi River! "Hi! My Name is "Cliff" drop over and see me sometime."