Scale rot...

What causes scale rot and wondering what it looks like in the begining? My guy has always had a very white belly and now it looks the very tiniest tan color. Also, is there a good book out that someone would reccomend for Ball Python keeping? Might be a good resource for all my questions and then I would not have to bother everyone here! Thanks!

First try this book... it has everything you need!!! Complete Ball Python: A Comprehensive Guide to Care, Breeding, and Genetic Mutations

Scale rot is usually caused by an abundance of moisture in your tank. Usually your snake will have something that looks like brown scaring. I am sure if you google it you can see some pics. I hope this helps!