[acdha]

Internet arbitrage caused quality to tank about a decade ago: any time there’s a sale, note the people cruising through checking prices on their phones so they can pick the books with significant resale value (the used bookstore owner probably does this too, if they’re still in business).

[WalterBright]

The thrift stores do that, too. However, I've found that a book's resale price has little correspondence with its quality - more like how many of them were printed.