In case you didn't notice, Wal-Marts are fucking huge. They don't have a Wal-Mart next to a bunch of mom and pop stores. They have them next to other big-box stores, Malls, Power Centres, or even Business Parks or Industrial areas. The land around them goes up in value.
And yes, I realize that Wal-Mart does damage some small businesses. Sorry, that's life. It's survival of the fittest. Change your business and adapt or face the consequences. Wal-Mart always made out to be the bad guy when Home Depot and Lowe's hurt hardware stores, Safeway, Whole Foods, etc hurt small grocers, and clothing chains (I could name a billion here) hurt boutique shops. Either come up with an original product or marketing strategy or move on. Sorry, its the way shit works.
Wal-Mart is not the worst company in the world ethics-wise. Because of their massive size they can dictate the sort of some products in the marketplace. Wal-Mart has, or will be very soon, halting the sale of farmed fish from their supercentres, and as a result you'll see a lot less fish farms in the world. It's also making changes to make their store operation more environmentally friendly. As many Vancouverites know, the proposed Wal-Mart in South Vancouver will have skylights to increase natural light and cut energy costs, have solar panels on the roof, built to a LEED Silver standard or higher, have solar, and collect and filter all waste water on site before it is sent into storm drains or the city system. Let's see any other retailer be even prepared to try that.
Oh, and the reason why Wal-Mart is so successful is not because they apparently treat their employees like shit, its because of their supply chain.