...more on the books.
my understanding is that book stores bore very little risk (so they didn't "buy" the books they got from distributors, they jst retailed them and split the profits with the distributor on each book actually sold). but when books didn't sell, they would only send back the torn-off cover (cuz no one wanted to pay to ship worthless books that weren't selling!). the distributor would just get the cover as proof that the book wasn't sold (and presumably destroyed).
under-handed book sellers would send back the torn-off covers, and then try and sell the books cheaply with no cover. sometimes old paperbacks will have a warning on the inside that said "if you have purchased this book without a cover, it was sold to you illegally and will result in your favorite book presses going out of business" or something like that.
...i always thought "drill holed" records were ones marked as promos for free distribution to radio stations and record stores. guess not.
also, i started a thread a while back debating how people thought about drill holes when buying/selling (in terms of degrading value). i don't even noticed them (unless in the run-out grooves!)