We brought one into the shop years ago. It was removed from a rental property. It looked brand new. We found out why. Running from front to back in the middle of the botton of the tank was a big black plastic cylinder. Everything was racked on one side or the other of this roller, plates and stuff running front to back, glasses, cups & bowls above. On each side of the lower rack was a detergent cup and a silverware basket. You filled both detergent cups. The first wash had the cylinder spinning in one direction. It very quitely "washed" the items on one side of the machine with the detergent that it washed out of the cup on that side. The second wash, washed the stuff on the other side of the machine. Then there were two rinses, one in each direction. After that there was food on the dishes. Not even smashed potatoes were washed from the plates. We did not let it go through dry.
After this reversing disaster, Tappan came out with the Reversa-Jet dishwasher. It had a wash arm in the bottom that was turned in one direction by the water jets. As it was turning, it was winding a spring that finally developed enough force to spin the wash arm in the opposite direction. This happened all through the cycle. After that, I think they put their reversing designer out of his misery.