Many books on any subject, including sex, really change when they are re-edited and new information is realized and used.
For instance, in Tristan Taormino's first edition of Anal Sex for Women
she used some information that we know is now incorrect, such as using Crisco as a lube on women. She corrected this, and other information and added more data in the second edition. I think older editions of non-fiction books are often outdated and probably should NOT be reviewed. It could give people a false sense of what a really good, re-written book is about.
"Printings" are different, because the information is the same, the printer just ran out of copies. Then an other "run" with the same exact data was released. In new "Editions" the books are re-edited or re-written. Two that come to mind, in addition to Tristan's are The New Bottoming Book
and The New Topping Book
which have not only radically different information, but the newer re-written editions are updated and have more information. In these cases, the books aren't even the same book. Someone doing a review for the older (not "new") books would be missing key pieces of the information the authors know now is correct and what they want to say.
Even fiction can suffer from this problem. The Story of "O"
was originally written in French. There are many different translations of this book, which read, in English like different books. Reviewing a translation different than the one Eden carries will again, give the person wanting to KNOW what the book is like and how the book is written improper information.
IMO, anyone reviewing books should be reading and reviewing the same exact edition (or translation) that Eden carries. After all, we aren't doing this for ourselves, we're doing it for the site and people who want the best information to make choices with their scarce resources of money. Right?