Complaining seems to help with walmart. Sheboygan's walmart usually has decent fish because there are a lot of activist people around. They even have a billboard in the pet section where you can hang information about puppy mills and about animal care and such. Appleton's walmarts aren't bad either and I usually buy from them.
Any store that gets shipments of fish once a week is going to have dead fish. Some stores are just more active in hiding it. I think your walmart just doesn't take much time in scooping dead fish because people don't care, or people spend money on pity fish.