Nobody will accept books which are written over like this, and she does that in her regular books as well, not only textbooks...While buying used books I get a lot of ones with notes written around in pencil, but usually in a way that doesnt go over the printed text, and you can either erease it or keep it, since writing in pencil is faint and doesn't disturb from reading much. What she does on the other hand, is just destroying those books in my opinion, they loose both their value and any aesthetics they may posses
Don't worry, books like that aren't going to waste I promise! I buy them all the time in second-hand shops.
Just two weeks ago I found Dante's Inferno AND Purgatory in a charity shop that had somebody else's notes all over them plus part of the first page missing where the previous owner's name had been written on, and I was so excited! As a bonus, they were the editions with the hideous neon green and orange print on the cover and spine.
I cannot tell you how happy I was! They had the Italian and English side by side and there were lots of interesting remarks in the margins about the translation, biblical references, allusions to other texts, interpretations, grammar, mythology, the lot. That person must have really studied that text in some depth. I'd love to know how they ended up in that shop. Oh and they smell soooo good!
I realise this is probably an unusual/unpopular opinion, but I really like pre-owned books that show evidence of having been used and loved. Scribbles, dog-ears, cracked spines, coffee stains, the uglier the better. So just remember one person's trash really is someone else's treasure!
I used to be one of those people who were all precious about their books and thought writing in them was akin to sacrilege, but... it's just paper. It's the contents that are important, and if any kind of physical interaction with a book helps the owner have a better and more profound reading experience, then the book is serving its purpose no matter what it looks like. And unless you are intending from the start to pass the book on to someone else, it should be yours to do with as you please.
We all know Ruby would never donate that book anyway, it will sit on her bookshelf gathering dust until the next time she rearranges her room, so she might as well exercise some critical thinking and make some notes on it.