The time spent on it easily amounts to more than the cost of replacing the very few books which may by chance be later found imperfect.

In fact, any responsible dealer will usually replace an imperfect copy with a good one even if the former bears a library mark, and has been handled a little.
Use care in cutting pages.

Don't cut them with anything but a smooth, dull edge.

Cut them at the top close to the fold in the back.
The worst enemies of books are careless people.
Another enemy is damp.

It is bad for the binding; it is very bad for the paper.
Gas, with heat, is very destructive to books, especially to the bindings.
Books should occasionally be taken from their shelves and wiped with a soft cloth.