I don't really shop at walmart much (it kind of stinks in there for some odd reason - my guess is that no one ever cleans up) but checking out the site, I've seen some people who do dress like that at Walmart a few times. I remember seeing a woman with hair rollers, pajamas, bathrobe and fuzzy bedroom slippers walking around shopping - this was in the afternoon. It kind of made me feel sad.
I feel bad for that woman in the pic - I don't think she knows that her back looks like that when she headed out. Some people don't check what their back looks like - just their front.