OK, my wife thinks I'm nuts as I go to each bathroom and waste water watching what happens with each flush.

Best ones for comparison are two toilets on opposite sides of a partition. One flushes in a clockwise direction, the other in a counter clockwise direction.

Neither toilet is level... but they are both slanted in the same direction, which doesn't account for the water exiting in opposite directions.

The ceiling under the bathrooms is the suspended type with removable panels. I opened 'er up to check out the pipes.

A main line comes between them, and an angled leg shoots off to each toilet (opposite directions from the trunk)

The water exits both toilets in the direction that is heading toward the angled drain pipe's opening.

However

the water that gets squirted into the bowl *IS* coming in at an angle, and in both cases the water swirls in that direction.

So in my mind the conclusion is crystal clear.

Spooks.

What else could it be?

https://www.dropbox.com/sh/ey71h8ep047758h/AAC12jNM0Hz9Q8zsh5iDeqNHa?dl=0