I find this funny. The lady was so willing to sell. She knew of the books “secrets”(I’m sure).
She knew they where worthless and wanted to get rid of them.
So they came with a few “surprises”.
Buyer beware.
To be honest, I would not mind a few hollowed out books of my own. Too much work to hallow one out yourself. Besides I got enough cuts and scrapes on my hands, don’t need more from digging out the pages in a hardback.