Just a random thought today: Our worn clothes are dirty. They have sweat, food stains, dirt, and fecal matter (undies). We shove these in the laundry machine, where those clothes touch the center spinner thing and the sides of the laundry machine. Even on high wash load, the water doesn't cover the center spinner thing completely, nor the sides of the machine, so any bacteria on our clothes remains on those parts. After wash, while our clothes are clean, they will rub up against parts of the machine the water didn't cover as we remove them and, in the process, get the dirty stuff from that on them. Now they are dirty again. Probably less dirty than pre-wash, but still dirty again.