I get the idea she lives in a small town and has never actually been to a Wal-Mart, and has more class than half the people I've seen shambling around in my local one the few times I've been dragged in there, simply for having the idea that people wear their sunday best there.
Though the idea that a person would think a bathrobe and foam flip-flops is "getting dressed up" and goes even lower than that when visiting a dollar store is pretty funny
