I believe the dishwasher is one of the best inventions ever. I have only had experience with low-end machines and I still feel this way. But over the past couple years I have found myself having to soak and re-do much of our drinkware by hand after glasses come out with the insides caked in various bits of food and grainy crud (for lack of a better phrase), which gets baked on during the heat cycle. I like to think I know my way around Google, but I've done search after search and have yet to find anyone who's had this particular problem (and had it resolved). The history behind this makes me think I must have something to do with it, but I know how to load the dishwasher correctly---i.e., following the visuals in the machine's manual and using common sense.
We just moved into a house whose dishwasher is a 10-year-old Whirlpool. It is very basic, but I thought, as long as it gets my dishes clean and doesn't flood the kitchen, I'll be grateful for anything. It did the job the first couple of loads, and the potent heat dry cycle was a happy surprise---the previous two machines were failures in that regard even with my religious use of Jet-Dry. But around the third load, it started happening again: when I go to unload after the cycle is finished, in the standing water in the bottom of cups (which of course are resting upside down in the top rack), there will be stuff in the water (cornmeal, a few rice grains, things we didn't even have on the dishes that load). But that doesn't bother me nearly so much as the nasty crud baked all along the sides of my tall glasses, and sometimes shorter glasses or bowls. It is completely random.
In our previous place, we inherited a fairly new dishwasher that did this every few loads, but began getting much worse and more frequent, so our landlord had a technician come. He said there was a lot of mildew in the hoses, and something else I can't remember, and that it would just have to be replaced. The landlord was understandably frustrated that the thing only lasted five years. She replaced it with a very basic machine (Whirlpool Silent Partner I). It was like $300, which seems to be about as low as you can go, and we joked about the name, because it was neither silent (anything but!) nor our partner in reliably getting the dishes clean and dry. However, this phenomenon I have described only happened every few cycles. Here at our new house, it is happening every time. Again, mostly just the top rack, tall glasses but sometimes bowls and shorter glasses, and the "crud" is made up of a nice mix of food particles that were removed from other dishes (NOT from the cups in question) baked into the dishes once the cycle is done.
So, has anyone else dealt with this...?