Or, more specifically, a hardcover book that I own, that sold many, many copies - but my version has a MAJOR typo in the titles on the spine (it’s a compilation of four books in one cover, leather).
My question - do such things as typos on otherwise good quality books cause the value to go UP or DOWN?
Depends on the rarity. If the typo is on every copy, the book won’t be any more valuable than if it hadn’t been there.
If this is just one particular edition of the book, the typo edition might be worth a little more than most others (other than the first edition, which is usually the most valuable), but probably not all that much more. Again, if 50,000 copies were printed with the typo, it wouldn’t have a big effect.
I don’t think book collectors are particularly interested in variant edition or typoes; their interest is in first editions.
What Chuck said, except that a few collectors do look for variants. Normally, though, these are of first editions of major names (people who get everything by James Joyce, say) or other special cases. Most four-in-one editions are cheap later compilations that most collectors won’t even look at.
But the best place to go look is at bookfinders.com, which is a meta-site that checks out books at 20 different used books sites. If a variant has a typo it will likely be included in the description and priced accordingly.