As of late the quality of (paperback in particular) books seems to have noticably dwindled and it does worry me... see-through pages, plasticky covers... Take for example Penguin. I own some books of their issuing from up to 84 years ago exactly and when cross-referencing with newer copies, there's a noticable difference in build and material grade. I can't seem to find proper resources on what's causing this decline, but I suppose it's not that surprising when a large company cuts corners. Still, I'd expect more self-respect.
Also pertaining to quality, I'd like to add that I respect what the Library of America does as a non-profit but the pages of their books are little more than squeaky tissue paper and even when I find one for incredibly cheap, I just can't buy it for fear of how uncomfortable it will be to read. God bless book scanners...
To end, I sincerely recommend corona/samizdat's catalog. Look upon it with great haste, reader. A thank you to Mr Rick Harsch.