Tricks of the used book trade

Excerpts from an essay at Slate entitled "Confessions of a used-book salesman":

I make a living buying and selling used books. I browse the racks of thrift stores and library book sales using an electronic bar-code scanner. I push the button, a red laser hops about, and an LCD screen lights up with the resale values. It feels like being God in his own tiny recreational casino; my judgments are sure and simple, and I always win because I have foreknowledge of all bad bets. The software I use tells me the going price, on Amazon Marketplace, of the title I just scanned, along with the all-important sales rank, so I know the book's prospects immediately. I turn a profit every time...

There is constant competition for the small minority of books that will not end up in the trash. Adults in cushiony white sneakers actually run into book-sale spaces at opening time, empty plastic bins raised over their heads. We all go as hard as we can until all the good books are gone...

With diligence, someone working alone can make $1,000 per week; with a more insane commitment, or with the help of a wife or child, the business might yield more, especially once a sizable inventory has been built up...

I see guys like this at our library's monthly used-book sales.  As fast as lightning, they pull books off the shelves, scan them and toss them into their huge baskets.  I find the entire process annoying, but it is of course quite legal and not really unethical.  Just annoying.  More details at the link.