My Walmart is also bad with their fish. They carry different types of Catfish, Goldfish, Feeder Fish, Algae Eaters and the male Betta's. I may have missed one or two types. All the tanks and cups with the Betta's are dirty, many of them are ill or dead. Its very noticeable. They just have no clue.
Your also right that some pets stores can be just as bad if not worse. Theres one by me where the fish tanks are clean, but extremely overloaded. The "closet room" for the mice,ferrets,gerbils,bunny's etc is extremely hot! The reptiles looked underweight/issues with shedding. My sister and I called animal control, they checked them, but they are still open. :( I refuse to go back there!
Those videos made me cry. :(