I have the following categories for my paperback collection: F, NF+, NF, NF-, VG+, VG, VG-, G, POOR. VG- is the lowest collectible grade. I upgrade whenever I have a chance. I keep track by assigning numbers to each book based on condition, then averaging. For example my Harlequin collection today is 567 books, including reprints, variants and a few extra copies. Each book has a condition grade and a number based on the following:
The average condition for the collection of 567 books is 1.217, essentially VG-. The median is 1.2. My ambition is a collection of at least 1.8.
Here is one of my fine books and one of my poor books.
Harlequin 353 - February 1956
Harlequin 356 back
Harlequin 81 - October 1950
Harlequin 81 back