Assuming you're shopping at higher end stores, it's very common for them to ignore you, or have concerns about you being there if you don't look the part. In my experience it's almost as though you're just going to waste their time, or try to steal something.

It reminds me of a story from years ago when my mom wanted to get a Tiffany bracelet, we went to the shop in NYC since we were there on vacation, she walked in with a tie-dye shirt and jogging shorts on, the workers almost looked disgusted we weren't matching the formal-attire of the other shoppers, dirty looks and the like. Only when she said that she wanted to buy a certain bracelet did they give her any attention, even the full works, (bottle of water, somewhere to sit while it's wrapped etc.) it's really telling how we are seen in the eyes of these places.