We bought our first High Efficiency washing machine 3 years ago. Over time, we noticed that our laundry (and laundry room) were becoming very smelly. It was the machine. We tried many things, including keeping the door open after finishing the load, used less detergent, being faster about rotating to the dryer... We also spent time reading up on some fancy stuff you can buy online (but didn't buy), yada yada. But it was something relatively simple that has caused the stink to cease.
I began adding about 2 Tbsp baking soda to most loads. I don't generally add it to my delicate laundry. Otherwise, I do add it. And since then I've not experienced the icky smell!
I have a flip top bucket that used to house my bulk Cascade dishwasher tablets (think Sam's Club), and I have reused it to keep the baking soda in. I put an old little snack bowl in there to use as a scoop. When I am ready I simply flip open the bucket, scoop, and put in the washer, right in with the liquid detergent.
I thought maybe this would help someone. If you have a laundry tip, please leave a comment!