Wait a sec, who debunked the egg-in-water test?????? I have found it to be totally accurate! We cruised on our boat in 3rd world tropical countries and I always did this when eggs were suspect and it always worked for me! Plus sailors without refrigeration have been doing it for, like, ever....
I'd be very curious to see where it was untrue.
Edited to add: I just googled it and found 3 pages that confirm that the egg-float test (in cool, unsalted water) works..... did not find anything questioning it at all......