My whirlpool duet washer has a terrible odor coming out of it. I have read about other people who have a similar problem. Is there any way to physically clean the machine? I have read about mold and fly problems and I'm afraid that I am about to experience the same thing.

I have had this problem and what I found that works is run a cycle with white vinegar every so many cycles.I think what happens is some water gets stuck in the washing machine drum an stays there and gets sort of a rotund stagnant smell. The vinegar will get rid of that smell and wash out your drum at the same time, you can also do this in your dishwasher to clean it up and make it smell good also.

Smelly Washer Cleaner is a completely organic powder that is used to clear fungus from any clothes washer. It works by disallowing cohesive properties between organic and synthetic compounds. The cleaner is used by adding a small amount (1 tablespoon normally suffices) to a hot setting in your washer and allowing it to complete the cycle.
In order to remove fungus spores from towels and clothing use just one teaspoon of cleaner instead of detergent. Rinse and dry as normal.
This product is super simple and works great! Find it at Washing Machine Cleaner