Front loading high efficiency washers have odor problems due to the buildup of mildew inside of the washer. Cleaning the gasket and the soap dispenser helps as does leaving the door open but these steps alone will not completely remove the mildew from the washer.
Step 1: The Drain Hose Problem.
There exists a design flaw in these washers and it is this. The exit of the discharge hose is much higher than the pump which is located at the lowest point in the washer.
Step 2: Baffle Drain/pump Area
This is the area under the washer tub where the pump, discharge hose and baffle drain hose are located. The baffle drain (second photo is a baffle drain removed from a washer)connects the stationary outer tub to the pump. So rinse water flows from the tub into the baffle drain, into the pump, where it is pushed up and out of the discharge hose. Except when the discharge cycle ends and the water trapped between the highest point of the discharge hose and the pump runs all the way back into the baffle hose and pump filter. The pump on the washer is not capable of completely displacing the rinse water in the hose.
Step 3: What Is Left in the Baffle Hose?
This is the rinse water I sucked out of the baffle hose using a wet/dry vac after completely finishing the entire cycle with an extra rinse. You can clearly see there is still detergent and lint present. There is about 1quart of water. No matter what you do you will always have at least this much detergent leftover. The detergent, lint and dark wet environment left by having the rinse/discharge water run back under the washer produces a perfect environment for mildew growth and that is exactly what happens.
Step 4: Removing the Remaining Rinse/discharge Water From the Washer.
To remove the rinse water from the bottom of the washer, you will need to suck it out with a fairly powerful wet/dry vac. I use a 6hp model. You will also need a hose adapter to mate the wet/dry vac hose to the washer's discharge hose. The part number is Rigid VT1407 available from Home Depot. Close the door to the washer, attach the suction hose from the wet/dry vac to the discharge hose and lift both hoses as high as you can. You will feel the water move through the hoses into the wet/dry vac cannister. It takes less than 30 sec. to completely remove all of the rinse water from the washer. After removal pour about 1 qt. of vinegar directly into the stainless steel tub and wait an hour. Suck out the vinegar and repeat the procedure. I perform this procedure weekly and my clothes smell the way you expect clean clothes to smell.