If I were running an anti-WalMart campaign (which will never happen), I would focus on the lack of selection. I would talk about how Wal-Mart's retail dominance minimizes consumer choice. Instead of telling people not to shop there because they pay low wages or put small stores out of business, I would make consumers feel like shopping there made their lives boring and mass-market. Clear Channel Radio suffered because the mass market approach to radio came to be viewed in a negative light. There was a movement that created new radio stations with the "one big company can't tell me what to listen to" attitude. Anti-Walmarters should adopt the "one big company can't tell me what to buy" attitude.
I believe I've been in a Wal-Mart two, maybe three times. They struck me as kind of dingy, a little junky. Of course, MN is the land where Target looms large. Comparing Wal-Mart to Target - no contest Target every time.