One of my professors was executive officer on the New Jersey (during WWII.) He said that he did this test (on various ships and in various ports) all over the world. Genrally (if the water had some time to relax), rotation went as predicted.
yeah, I read on snopes that which tap you turned on had a lot of effect for some considerable time.
Similarly, most Southern hemisphere toilets, et al, are modeled (literally, same mold) after their Northern brethren (which have a twirl to them to re-inforce the Northern effect), and so spin accordingly.