A lot of these shops are basically just big closets full of some hoarders' junk. It's marginally better than an empty storefront, but not by much.

Funny enough an acquaintance used to volunteer at one and his main income (aside from the dole) was finding the good stuff, taking it, and selling it on ebay (he was delighted when someone's old school Game Boy with original pokemon cartridges came in one day...).