Thank you to everybody for responding.
Here is the update re repair people:
The first repair guy thought it was the drains. The second repair company had heard of this problem (smelly washer) but didn't know what to do about it.
The third washer repair guy had seen this before. It wasn't the sewer pipe or the drain (both were checked and not clogged)--it was too much detergent and using (even occasionally) liquid fabric softener in a front-loading machine. (Just like what the others in this thread said.)
The washer repair guy had recommended 10 bleach cycles. Two were done, but concerned about damage by the bleach, and based on a recommendation in this thread, 4 PureWasher cycles were done. Unfortunately, it is a long process where 1 "cycle" involved first soaking for 2-4 hours, then soaking overnight, then rinsing a few times. If the smell was less bad, it wouldn't have been so many times. But now the horrible smell is finally gone.
We have also switched to HE powder detergent, which was recommended in other net resources I found. Using less than a quarter-cup of the HE powder was plenty in this high-capacity machine. For cold water washing, I keep a wide-mouth water bottle (the kind that bicyclists use), and dissolve the powder in some hot tap water, shaking it up before pouring it in. Has anybody seen an HE cold-water formula powder?
From everything I've read so far, including suggestions provided by the kind folks in this thread, to prevent possible bad smells developing in frontloading washing machines, this is what is suggested:
1) Leave the door open between washings;
2) Use the right kind of detergent (HE, and possibly, use only powder, even though the SDA says liquid HE is okay);
3) Use small amounts of HE detergent, even less than the directions indicate;
4) Do not use liquid fabric softener (even though the SDA says it is okay)
The Soap and Detergent Association (SDA, an industry group) has a fact sheet that discusses the possible consequences of using non-HE detergent in HE (frontloading) washers, as well as maintenance tips:
http://www.sdahq.org/laundry/HE.pdf
Is there any way for Consumer Reports or somebody to do a report on this so all new bu...[Message truncated]