Garbage isn’t a value judgment: His company, along with several other enormous used-book-selling operations that have popped up online in the past decade, is literally buying garbage. Thrift stores like Goodwill receive many more donations than they can physically accommodate. Employees rifle through donations, pick out the stuff that is most likely to sell and send the rest to a landfill. The same thing happens at public libraries; they can take only as many donations as their space and storage will allow, so eventually they have to dispose of books, too. (For libraries, the process is a little more complicated; they can’t legally sell books, so they essentially launder them through groups with names like Friends of the Library, which sell the discards and donate the proceeds to the library.)
I’ve bought quite a few books from the local Friends of the Library, but I’d never really thought of it in those terms.