That it's not perfectly reproducible should be setting off alarm bells, even for people who would really like this effect to work at the scale of a few metres.
AIUI the math is that the delta in acceleration across a 1m bathtub north-to-south would be 1x10-8 m/s/s due to Coriolis ... so your starting conditions would have to be at a level of perfection that I don't think anyone's achieved, certainly not some bloke in a drafty garage with a kiddy's wading pool one time.
I accept that in theory that delta definitely exists, but I don't accept that it can be, has ever been, observed at the tiny scales of a few metres, let alone the 100mm (toilet flushes) that's typically asserted by the faithful.
I accept that across dozens of kilometres we definitely do see this phenomenon as it generates consistent, hemisphere-dependent, large wind events (eg hurricanes) once you get a good way from the equator.
It's probably reproducible in the sense that if you do it a 100 times you get a strong statistically significant effect. They were probably unlucky that day.
