If you are going to collect books as physical objects, rather than their much more convenient digital versions, then it strikes me you should actually find the signs of previous interactions with that object (library stamps, marks from other readers etc) make them more interesting than pristine copies that no one has read.
That runs very much counter to how collectors actually collect books currently. The more pristine the book, the better, aside from particularly rare or valuable inscriptions.
You bring up a good point about physical vs digital.
I'm still not sure if my children for example, understands that when I'm staring at an iPad I'm almost always reading a book. Does a vast library in iBooks translate to them as well as the same library on physical books in a bookshelf in the house? My sense is it does not.
And when I'm gone, will anyone find any interest in my iBook library? In its highlights and notes? In the books I've read and re-read dozens of times?
Some of my fondest memories are going over my older or deceased family members' book shelves. I have never, however, gone over anyone's tablet. Part of that is because it's newer, but something about the browse-ability of an e-book misses the mark. I can't see which book is worn from being read and re-read, or brimming with notes and scribbles. In digital, it's hard to tell which books that person found significant, but in physical it's obvious by the condition (or even number of copies) of the book.
One of my most treasured books is a copy of Goethe's _Faust_ (in translation) with notes from a nun.
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Personally I do like these marks. But I buy books to read, not as an investment. I recently bought a book on "How to survive being gassed" published in 1934. It had a typed A4 sheet of paper in it with a poem about how to identify the different types of gas. Humourous and probably useless but real and very alive.
I also take umberidge with the idea that digital books are more convenient. A physical book is more engaging, more beautiful, more real and more present than a digital book. All things that I find convenient when I want to interact with knowledge and art. Horses for courses I assume.