I co-own a house whose neighborhood is almost adjacent to a Walmart, which shares a run-down shopping center with a Target and a Costco. The house isn't close enough to be directly affected, but it is worth mentioning that as the shopping center has slipped (it once was the city's nicest centrally located mall, housing a Bullock's and a Dillard's), the surrounding residential areas have not been helped.

Slightly tangentially: friends owned a house that backed onto a large, downscale supermarket. When the couple had a new house built at the top of the bubble, they ill-advisedly decided not to sell while before the developer completed the construction. Their new place wasn't finished until after the real estate market collapsed, and so when time came to move, they were stuck with two houses. Though houses a block or two away from the store sold (sooner or later), they could not sell theirs. After two or three years of struggling to sell it and keep it rented (no, renters don't want to live next to a grocery store where wee-hours garbage collection sounds like a wrecking yard and the homeless mentally ill camping in the parking lot throw garbage and human waste over the wall into the backyard at night), they finally were forced to default. The bank hasn't been able to sell the place, either.

Walmart, because of the nature of its clientele, has no motivation to upgrade a shopping center. They want a scruffy, low-rent effect: that helps attract people looking for rock-bottom prices. As for nearby housing: lie down with a dog and you get up with fleas.