It's rare to see anyone "dressed up" to go shopping regardless of the store. I live in a very upscale area and I see women all the time in ripped jeans, old T-shirts and carrying LV (coming out of $2-3 million homes so I believe the LVs are real).
If I saw someone wearing their best clothes on a Saturday morning to go to LV or any other store I'd think they felt they had to prove something to the SA's.
This reminds me of a story DH told me - he cares about quality in some things, just doesn't see it in bags (but he's getting better about that). Anyway he needed some new sunglasses and went in an upscale store wearing old, stained clothes. The SA said "you know these start at $200, are you sure you're interested?" So he pulled out his mangled ones and said, "yes, I paid $450 for these and I stepped on them today while working at a charity building site, which is why I'm dressed like a bum, but I'll go elsewhere to replace them" and he walked out.
Once again I feel ancient - my mother used to wear a nice dress, high heels, GLOVES and a HAT to go grocery shopping in the 60's - I don't know anyone who even dresses like that at church anymore!