KA scale issues (my friends' machine, not mine)
what's in it? a mild acid? I wonder if citric acid would have done the trick. I descale my washer and dishwasher four times a year with 1/4-1/3 cup of citric acid powder. My main objective is primarily descaling of the pump and plumbing inside the machine, and secondarily to shine up the SS interior, though to be honest I never get any visible residue or scale inside the machine (Bosch).
Oddly enough, I have friends in the same town (same water system) with a high end KA, three years old maybe, and they always seem to have scale in their SS interior. They chose KA over Bosch because of KA's food disposer; at the time of purchase, they still had three kids at home, though today only one is still in high school. However, their old, poorly performing DW was so bad that they had to pre-rinse everything, so I doubt if the KA's disposer even gets all that much business. But I think a concern was if the kids threw in dishes that weren't scraped or pre-rinsed (never happens, mom pre-rinses EVERYTHING).
They gave up using Finish tabs because their detergent dispenser door wouldn't always close securely (tabs were too thick for door to close) and I think are using liquid. I advised them to use powder over liquids if the tabs didn't fit, but I think they use liquid (and they recently gave me three giant Costco canisters of Finish tabs which they can't use). Their DW always has scale on the interior, even with descaling with citric acid (I gave them a container of it as a thank you for the Finish canisters). Their dishes do come out clean. I am not sure if they use JetDry but I think they do use it. I can't figure out though why their interior always looks terrible, even after the end of a cycle.