Thrift stores in rich neighborhoods have significantly higher quality of items than ones in poor neighborhoods. I would not recommend shopping at poor thrift stores.
I sometimes go to thrift stores when visiting new places just to see what is there and my experience is different. Goodwill/thrift stores in richer cities/areas are better. I went to a goodwill in Atlanta in a poorer area in May and the clothes we pretty worn. The prices were cheaper but you can't fake being middle class in most of the stuff sold there. You will just look poor and that's how many would treat you.
Then you haven't been to an actually poor one. Every single one I've been to looks like that one room in an old person's house, full of stuff that no one could absolutely give a shit about and priced WAY the fuck over what it should be.
In my experience, this is true for just about every type of store. Especially grocery stores. I live on Federal in Denver, and the selection relative to some of the wealthier suburbs is atrocious. The past few years have made me wonder who gets the job of ensuring poor neighborhoods get screwed in the face of nationwide shortages of items.
Fine, the pursuit of profit over all else forces people to make decisions like screwing entire neighborhoods out of access to basic quality food and other goods.