Almost every time I buy a book listed as "Very Good" which has a clear definition on AbeBooks' website, I end up getting something with clear markings, or damage.
But it's amazing to see this level of automation and scale. My father was manually cataloguing everything and then selling ex-library books for at least a few dollars apiece (often more based on rarity). The dealers profiled here are able to do this on a scale orders of magnitude larger, and cheaper, than a small-scale bookdealer could do by hand -- at least without barcodes.
The barcodes, as mentioned in the article, are a huge deal in that they can change some kinds of cataloguing from minutes of labor to seconds of labor. But ISBNs themselves were only invented in the early 1970s and bar codes on books weren't common until the 1980s. Depending on what decade the books you're dealing with are from, the level of automation of cataloguing could also vary quite a lot.
One thing you'll also see (which antagonized my father quite a bit as a dealer but which can definitely be seen as a huge boon for readers) is that individual people will go to huge sales, like library sales, at the earliest possible moment with phone apps and try to scan thousands of books to find those that will sell at enough of a premium above the sale price to be worth buying. Traditional dealers with brick-and-mortar shops and/or specialized knowledge of some area have some rather negative terms for these competitors, who notably may not have a lot of personal knowledge of the books they're reselling, but do have a lot of dexterity and access to big online databases.
In general, online databases and subsequently mobile apps have done a lot to make the used book market much more competitive, and also much more accessible for smaller-scale participation by non-experts. That's often a hard thing for used book shops and a useful thing for readers.
Library discards or "deaccessionment" are still a sad thing to me, and I think to most librarians too, although they'll often point out that many volumes that are being deaccessioned haven't been checked out in years. A good thing for preservation is that the Internet Archive now acquires a lot of these volumes in various ways and scans them with the goal of getting them online.
There are absolutely books still being thrown in the trash all the time that would be worth hundreds or thousands of dollars to the right buyer, but they're also an incredibly tiny fraction of the books that are thrown away.
> how many books are "lost" because of some scanning fault
Scanning processes are getting better and better, so I also think this is a diminishing problem.
Nicholson Baker wrote a fascinating book called Double Fold in which he pointed out that paper books are typically much more durable than many people think¹, and that digitization and imaging projects have significant drawbacks and limitations. Librarians were quite annoyed with this book because it attacked them as negligent stewards of history. I don't think Baker's arguments have aged very well, as current scanning options are much better and have produced much more useful results than many of those he attacked.
¹ This is true -- Baker points out that our intuitions about fragile paper are mostly shaped by a few decades in the 20th century in which the use of high-acid paper became common for cheap mass-market books, and also for newspapers and magazines. Most older books were printed on lower-acid paper which often lasts for many centuries without major degradation. I have a number of books from the 1700s that are still in great shape and can be read by hand without damaging them (though most have been rebound, because the bindings are normally more fragile than the pages).
At a used bookstore recently (in Hobart Book Village), my too-young-to-read daughter took a fancy to _The Life of a Bear_, probably because of its 24 illustrated prints involving bears. After realizing it was a ~120 year old book and gently extracting it before she removed one of the pictures, I became slightly fascinated with it.
It appears to be a perfectly cromulent children's chapter book, of similar vintage and theme to _Black Beauty_. Its author was anonymous; in the edition I have, he is simply referred to as "by the author of 'The Life of an Elephant'", the author of which was referred to as "by the author of 'The Life of a Bear'." You can find reprints on Amazon by one of the "reprint any out of copyright books" companies, and a half dozen old editions on ABE.
After much detective work and the WorldCat database, and the assistance of a professional librarian, I did eventually discover the author to be apparently one Sir S Eardley-Wilmot, who was a naval officer at the time (hence the anonymous publishing; it probably didn't pay to be "the naval officer who writes children's books"); he did apparently republish the books under his own name, after he retired, and a third book "The Life of a Tiger" was eventually published, maybe posthumously. He even gets his own Wikipedia article, which mentions the books he wrote on military history, but not his children's offerings.
So anyway, the point of the anecdote.
One point I could make is on the ineffable mystery of why some books are cultural classics and others aren't; why is _Black Beauty_ still beloved by millions, and _The Life of a Bear_ forgotten? Is it purely a matter of artistic merit, do people just like horses more than bears, is there an underlying message to Black Beauty I don't remember since reading it 30 years ago that resonates?
Another point I could make is on the surprising robustness of this print volume, as you mentioned. It has probably been forgotten for a hundred years, not particularly well cared for, just thrown on a shelf somewhere and still in good enough shape.
Or it could be on the inanity of most of the books we are slowly forgetting. Does it really matter if this children's story about a bear vanishes from the Earth? Has our culture been lessened, did we forget something important we once knew, are people less happy for not having read this book?
But what really sticks with me is something completely different: this book is not in the long tail of books. Maybe not the fat head, but solidly in the chubby middle. It received many print editions from multiple publishers on different continents over the course of 30, 40 years. It's in multiple libraries; it's been digitized and is available for reprint at the push of a button. It's probably in the top 10 million of the ~130 million books ever published.
Can you imagine what is in the bottom ~120 million books?
* Black Beauty is a phenomenally well-written book, with fair comparisons to Bronte, Hardy and Dickens; and is certainly not viewed as a "children's book"
* written about horses at a time when horses were the world's most owned animal;
* and also at a bleak moment in the Industrial Revolution when the workhouse, child labor, and workplace hazards were at a local maximum.
So a fair mix of good timing and subject matter, combined with an excellent execution.
Anyway tldr everyone should re-read Black Beauty.
But I'm a big fan of paper books and I have a lot of them and buy more of them regularly.
The sales are mostly resellers trying to find value. In some ways that's a good think making a market for books people want at a reduced price, but it is also frustrating being someone who wants to acquire books to read competing with people trying to make a few dollars.
After a few months a copy turned up on ebay for $15. I looked into the seller, thrift.books (mentioned in this story), decided I wasn't taking advantage of a little mom-and-pop bookseller, and purchased it. It was indeed a little trade paperback.
While most of this type of book would go for a penny, this one is valued much higher because of the chemical recipes. The author was somewhat miffed at the profiteering taking place in his industry, and told his audience how to reap the benefits of the book without being ripped off.