Book maintenance is really a very troublesome thing. If your book corner and the number of books are small, it will basically be maintained and the cost will not be very high.
As long as the borrower is asked not to smear at will, it is good to keep it clean. However, if there are a lot of books in your corner, I suggest you learn from the handling methods of many second-hand book platforms.
Prepare some professional disinfection tools, such as sandpaper and disinfectant. It takes some time to deal with the dirty places on the margins or corners of books and wipe off the stains on the cover of books.