Honestly, it depends on the SA. One time I walked in wearing my marc by marc jacobs bag and sunglasses, jeans and t shirt, I tell you, they see everything you wear! (And I almost always dont care about how I dress when Im purely shopping and know what I wanna get!) Anyway, that day I was looking for a costume jewellery necklace as a gift for my little sister's grad and I literally had to beg her to show me what kind of styles she had! Other times when I pop by after work and I'm wearing a suit, killer heels and bag, Im followed around and treated like a queen.
All that said, I actually prefer being dressed like a bum because I like to be on the downlow when I am searching to buy something. Very rarely do I buy something because the SA has talked my ears off or "convinced" me to.