The Mystery Spot is a very odd place. For example, they have a weight hanging from a chain, making a pendelum. Now, everywhere else on earth, if you take a weight that is hanging straight down and pull it back 1 foot and release it, it will travel through the center point (where it was hanging) and go past about 1 foot. No so at the Mystery Spot. The weight goes about 2 inches past the center point, then rockets back at you. Yet, it eventually comes to rest at the center point. I too assumed this was an optical illusion, but testing, using a marker to indicate the "at rest" position proves this is not so.
Another one: they have two pieces of steel about 4" wide and about 18" long cemented into the ground parallel with each other. They have a number of bubble levels that can be placed at any angle or combination, turned around, flipped over, etc., and all show these to be level. They let you do all of this testing, and one guy even brought out his own small level. Then, they pick out two people, one to stand on each rail facing the other. "Okay, what's your point?" you think. Then they tell you to switch rails, and suddenly your relative heights are radically different. I was even with the person opposite me, then when we switched, I was about a foot taller.
Oh, and then there's the "spout" that you'd swear was running down hill, that the bubble level showed to be level, but caused a golf ball to roll UPhill.
It's a strange place, all right.
-Troy