Analyse the binding style of the books you’ve collected. How does the book block adhere to the cover? How does it adhere to the spine? Is it stitched or glued? You’ll notice that in case-bound or hardback books, the sections, or signatures, are sewn together and glued to the spine. Paperback books, on the other hand, are more likely to be ’perfect-bound’, where the pages are glued together and then directly onto the covering.
Scarfolk Annual – Richard Littler (hardback)
The book block is not attached to the spine in this book. Instead, the endpapers are glued to the cover and attached that way. It looks like the signatures have been sewn together and attached to a piece of material at the back.
Met Office Pocket Cloud Book – Richard Hamblyn (hardback)
This book also has endpapers glued onto the cover. Unlike the previous book, this book block does seem to be glued onto the spine as well. The signatures are sewn together and then it appears that they are glued onto the endpaper.
Francis Bacon: Phaidon Focus – Martin Hammer (hardback)
The signature are sewn together and then sewn onto a piece of fabric. The fabric is then attached to the side of the spine. The endpaper is also glued onto the cover.
Wild Signs and Star Paths – Tristan Gooley (paperback)

As with all of the other paperback books in my collection I have found this one to be perfect bound. The pages are all glued directly onto the cover.
One thing I have noticed is that perfect bound books don’t open as fully as their sewn counterparts. This is definitely a factor to consider if a book has imagery inside.