A couple of things:
1) Here are some more references.
J.S. Mills, R.White. The Organic Chemistry of Museum Objects 2nd ed. Butterworth-Heinemann, London 1994.
H. Kühn. Conservation and Restoration of Works of Art and Antiquities. Butterworths, London 1986.
J.M. Cronyn The Elements of Archaeological Conservation Routledge, London 1990.
2) A good way to spot (some) cleaning is to look on the inside of the covers. If the red ink from the outside cover has bled through to the inside, it has likely been cleaned or had tape removal. The solvent that the paper is immersed in solublizes the inks and allows for migration. Red is the most common ink, but green and blue do it as well.
3) Great discussion on trimming, but one addition is that the right edge and bottom edge should form a "V" pointing out of the book, while the top edge should form a "V" pointing into the book.