I received a question on my radio show from a listener who had a brand new washing machine that gave off a dirty sock smell. He would bleach it out but it kept coming back. So he called the manufacturer and the manufacturer said that was normal if you were using cold water! That's a bit of a shock when we are working so much on energy conservation, so I got on the horn to my industry contacts to find out what was going on.
It turns out that washing machines have changed, because people wanted them to be more and more 'maintenance free'. Remember the old lint trap? Right, you had to keep it clean. So with time, the lint trap disappeared and we just flush the lint down the drain. To do this they improved the pumps so that they wouldn't get clogged up. But it means that we have more lint flowing through the system than in the good old days.
HOW COLD IS COLD WATER?
Second, it turns out that most soap doesn't activate properly unless the water is above 70 degrees F ( 21 C ). Right, even the 'Cold Water' soaps. In Canada, at least in the winter, that means that we should not use cold water only, but at least 'warm' water for the washing cycle. It is apparently OK to use the cold water for the rinse cycle. It turns out that some of the modern washing machines cheat and when you call for 'cold wash' it actually is tempered with a bit of hot water to get above 70 degrees to avoid the 'smelly socks' problem. But if you only turn on the cold water faucet, it can't cheat and the soap is too cold to activate properly. Add to that the comment from the washing machine repair people that people generally use far too much soap. You should just have a suggestion of suds during the wash cycle, not a good frothy foam.
HIDDEN LINT IS THE PROBLEM
Combine too much soap, cold water and no lint filter, and you accumulate a coating of lint between the two barrels where you can't clean it out. That is what is giving the dirty sock smell. So limit the soap, use a warm water wash, or an occasional but regular hot water wash to flush the system, and leave the lid open a few hours after washing to let it all dry out. I love that recommendation. My wife always complains that I haven't finished the job if I leave the lid open, but now we find out that's the healthy thing to do!
I am not sure if all of this is progress or just a manifestation of our laziness in not wanting to clean out lint filters, but it looks like we have to adjust to live with it, or buy more air freshener spray.