I recently received an older hardback.  I RWAP'd it because of the binding.

On the inside cover of the book (both front and back).  The threads are the only thing holding the book together (the paper has ripped/separated across the entire crease).  In addition tape (which does appear to be the acid free type but you never can tell).  Has been used to cover this portion of the book.

I didn't ask for my credit back as the book is in good shape other than this & I have the knowledge and materials to repair it for my own bookshelf (I had no intention of reposting the book to begin with).  I stated all of this in a PM to the individual along with the note sent by RWAP, along with a note to respond so that I could know that they had received the message and I could mark the matter resolved.

In the response I received I got the usual "I send and receive books in this condition all the time" type of response.  So, getting my ducks in a row, I went and checked out the specific wording used for the "good" condition guidelines to a) make sure I'm in the right (I can eat crow if I need to), and b) find out the best way to explain to the individual what they have done wrong in my final PM to them.  I was woefully depressed at the inadequacy of the explanation in the help docs.

Binding:

• Must be intact, with no separation on the inside or outside of the book
• If the book tends to open at a particular page, this is OKAY
• Small amount of fraying or denting at top or bottom is OKAY

So am I correct, and how do I best explain to this individual why this is a problem.

Note that with the exception of their last post (which may simply be a defensive reaction which we are all prone to) the trade has been very cordial and I have no problems with the individual.  They even sent me a PM informing me that they no longer had the dust jacket for the book prior to mailing it.  They are not a really old member but neither are they a new member.

Perhaps this old discussion topic will help:   Definition of Binding Separation Discussion

It discusses cleaving and the amount of book separation that is acceptable for postable books, and includes information on the topic from the site administrators.

That is a good reference

Does anyone have a reference for hardbacks (the only threads I found that covered hardbacks were for excessive wear, which this book does not have).