Without anyone saying a word to you, when you see a paperback next to from another bound in cloth or leather, you realize right away that the first it is less resistant and less expensive than the second.
According to an old saying, a book is not judged by its cover, This is true if it refers to the content of a book and whether it is good or bad.
Many of the best books in the world have been published in paperbacks, and never you can say that a book is not good just because it is not good bound.
What can be said, looking at the cover, is if a book on your part material will last a long time or not.