After five years of wrestling with this problem, we finally hired an experienced professional with 40 years' appliance installation experience. He found that the builder's subs had not installed the dishwasher properly 6 years ago, and had not followed the manufacturer's instructions as to the location and height of the drain hoses. Debris from the disposal had been backing up into the drain hoses and rotting there. Our dishes were very clean and safe since the gunk was in the drain hoses, but the smell was horrible. We had tried so many other solutions over the years and they each helped a bit so we had thought we were done with the problem, but now I know we are. The hoses he replaced looked like clogged arteries.