At least the first Maytag lint filters were advertised as detergent dispensers so there was some chance that they would be pulled at the start of each load when detergent was added. I also believe that back in the late 50s people cared for their machines better than they do today. For many, it was their first automatic and represented a large investment that was supposed to last.
An even grosser situation can usually be found just above the lint filter in the residue under the fabric softener cup when that part of the filter was never rinsed out.
I also see a lot of mineral buildup in this filter. It was the move to non-phosphated detergents that caused widespread clogging of lint filters and caused Maytag and others to virtually eliminate them by going to the largely ineffective but hidden synthetic screens and grids under the agitator. As long as people were not cleaning the filters and mineral clogging was rendering them ineffective, manufacturers could claim to have hidden, self-cleaning filters whether they worked well or not. In the early days of filters, before many people had dryers, their effect was more noticeable. Now, most lint is removed in the dryer. The Maytag filter like other agitator-mounted filters, such as on some Hotpoint, Speed Queen and a few other washers, was less effective than the ones that relied on water circulation by the pump and did not even function at the lowest water level. Of course, the Filter Flo system did not work unless the tub was filled to the full water level in the solid tub GE washers. After a few years, the rubber collar on the agitator of the GE's would wear to where it did not hold the metal filter pan securely and the pan would tip back toward the filter inlet flume during agitation compromising filtering by allowing water to spill out over the side as well as not utilizing the whole filtering surface of the filter pan. CU reported that the non-self-cleaning filter in late 50s Kenmores could cause flooding if not properly maintained.
