It's my belief that other than sexually mature adults during breeding season (males more than females), most ball python fasts are directly related to husbandry issues.
I don't sell hatchlings before they have reliably fed three times in a row for me at a minimum. I have made an exception for an experienced breeder friend, but for most buyers, I have to know that they WILL eat, so that if they don't eat in their new home, we can address what's different about their set up and what might be putting the animal off of feeding.
In our caresheet, there's a check list of items to check off if your snake doesn't feed for you called "Why won't my snake eat?"
http://ball-pythons.net/forums/showt...ius)-Caresheet