The Kroc wrote:
Front load washers retain about a cup of used water at the end of the wash, Newer washers have a hose that drains this dirty water. Over time, the bacteria interacts with the soap scum to produce a foul odor, I would not buy a front load washer until the manufacturer's solve this problem
The only water that is retained is past the pump in the drain hose. It can NOT get back in the washer because there is a one way valve there on the outlet side of the pump.
Some of the older Maytag washers did not have a drain hose on the door seal, but most of those are long gone to scrap. The door seal can be changed out to the newer style with a drain.