Books with zero listings give them nothing to work with, nothing to undercut. Left to their own devices they usually cough up comically wild-eyed bugnuts prices- $383.41, for example, a real price I just came across for a cool but not exceptional metaphysics book.
These prices sell my books, so I love them.
One advantage to learning the trade the old fashioned way, in a retail store over many years, is a solid sense of what books are worth. To cop an aviation metaphor, scanner people are used to a flight simulator and if the autopilot craps out they're completely screwed. Whereas a grizzled old school book dealer of my stripe is used to flying by feel, relying on their own senses.
We had references of course, auction catalogs, price guides and the old reliable Books in Print, but as impressive as the Wall of Knowledge looked behind the counter it wasn't all that practical when you were facing down a huge 20 box buy.
In buying, you learn to quickly and efficiently sort the salable books from the rest.
Pricing out those salable books requires accurately and swiftly separating out the average, solid stock from the interesting, exceptional stuff. Once you've priced out the stock you can pay closer attention to what's left.
That part of the job is a cakewalk now- you check the title online, sniff around a little to ensure the listed prices are reasonable, and that's it. Whatever opinion you have of the book as an object, for most customers in the smartphone era it's "worth" whatever Amazon says its worth.
In the old days you had to make an informed decision based only off the information in hand- author, publisher, cover copy, a quick flip through the body of the text. After all my years in the business I do this so unconsciously that to most people it looks like a magic trick. A quick glance at the spine of most books is enough to tell me if it's worth my time or not. When I'm buying over the counter I have to make myself slow down- people get upset if it looks you're not paying close enough attention to their books, especially when you usually end up rejecting 9/10ths of them.
As Teller says about successful magic,
Make the secret a lot more trouble than the trick seems worth. You will be fooled by a trick if it involves more time, money and practice than you (or any other sane onlooker) would be willing to invest. My partner, Penn, and I once produced 500 live cockroaches from a top hat on the desk of talk-show host David Letterman. To prepare this took weeks. We hired an entomologist who provided slow-moving, camera-friendly cockroaches (the kind from under your stove don’t hang around for close-ups) and taught us to pick the bugs up without screaming like preadolescent girls. Then we built a secret compartment out of foam-core (one of the few materials cockroaches can’t cling to) and worked out a devious routine for sneaking the compartment into the hat. More trouble than the trick was worth? To you, probably. But not to magicians.
I can clear a table at a library sale of every faintly saleable book in just a few seconds because I've spent literal years honing an acute, specific type book sense- that's my version of producing 500 cockroaches on a talk show. But unlike a proficiency with stage magic, my talent has been rendered largely irrelevant by modern technology. You'll hopefully forgive me for being inordinately pleased on those occasions when it still comes in handy, as with our $383.41 book.
So, I spotted the book on the shelf, pegged it as a solid $30-40 item and paid the nice thrift store lady her two bucks . In this case I'm correct and the internet is wrong- there's no way it's a $300 book. It's not even a $100 book. How do I know? Because I've seen enough genuinely rare, expensive books on metaphysics to know how they look and feel.
So I've got a $30 book. But thanks to crazy people (or more likely, their book program's crazy pricing algorithm) I know, know I'll get $60 for it.
Because someone familiar with the book will eventually come along, say to themselves "Man, sixty bucks is pretty steep!" then notice the other copies are $300 plus and JUMP on my copy.
Thank you, scanner trolls!