Yes, this.

Even hardcover books from "real publishers" have arrived with low print quality. The most common problem book-printing problems I have a real problem with today are

  1. text that is gray (not black) and
  2. text that is dotted (not solid)

I have, 20, 40, and 100+ year old books with phenomenal "solid black text", and they are an absolute pleasure to feast the eyes on. But more importantly, they are not so irritatingly bad while reading them that the bad presentation entirely and unavoidably distracts from the quick and enjoyable consumption of the content itself!

If you ask me, the following checkboxes should be standard ratings on all books sold:

  [ ] "solid, black text"
  [ ] "acid-free paper"
  [ ] <we could add a few here>

Everything else comes after knowing these aspects in my opinion. I guess these would require numeric, measured scores, too, with the binary checkboxes indicating some minimum threshold is surpassed. There are other important factors, too, of course, but getting basic text color and text character solidness is number one, easily.

Related, I used to buy 3rd party black laser printer toner that was guaranteed and warrantied to be made to OEM spec. It never, ever was, no matter how many returns/replacements/retries/print-settings-adjustments/other-part-replacements. Always gray text, always. Buying actual OEM black toner reliably results in (close enough to) jet black text. It costs more, but it's the only way to be sure for self-printed materials AFAIAA.