With the greatest respect. I love books!
They were kept in pristine condition, when I had my 'Library' in my Lounge Room, at my original, beautiful house. Now they're all in packing cases, unfortunately!
My 'day to day' books I buy, are kept in their purchase plastic bag to keep them clean.
Get many books from Council Library, & get REALLY annoyed when I see a crease of turned down page! Lazy people! A bookmark can be anything from a Woolies' docket to a purchased beauty, so to me, there's NO excuse WHATSOEVER to turn down the page of a book!
I try & 'iron' out the crease, if I can.
It's very rare for me to write in a book. I much prefer to keep them unblemished!