I’ve been to a few of the mystery houses with the slanting floor, but I’ve never been to the Oregon Vortex, so I know not directly of which I speak. With that disclaimer aside, while I’m sure there’s a slanting floor house at the Oregon Vortex, I was under the impression there’s more to it than that. I don’t have the book with me, but IIRC, James Randi mentions the vortex, at least in passing, in his book Flim-Flam. The impression the book gave me was that there’s a natural occuring area there where the laws of gravity seem to be violated. Randi’s explanation was that it was probably due to a few factors (possibly due to some past earthquake), such as sloping ground, along with trees growing at a slant, the combination of which throws off your visual perception of up and down. I was also under the impression that the result of this is so profound as to actually affect your sense of balance.