Stainless Steel Kitchen Aid
We had a Superba--darn good dishwasher--and replaced it with another TOL Kitchen Aid that, unfortunately, hasn't held-up as well.
With the old Kitchen Aid--it had a speckled blue and white interior--the thing never stained. Never.
I'm not sure why, though. Perhaps it was porcelain (?).
I know other folks who have bought Kenmore and Maytag DW's and they have stained with spaghetti sauce, etc.
Never had that problem with a KA.