In a lot of cases, I can tell if I’m in a good neighborhood if there’s self checkout. All the stores around here in bad neighborhoods never got them.
I too use that to judge, and how many carts are left loose in the parking lot vs. carts in the holding cages.
Stores in bad neighborhoods also seem to have a lot less inventory on the shelves, frequently with empty sections. This may just be an indicator of a larger shopping population, though, as the rough neighborhoods are usually in high-population density areas.