Snakes aren't bad feeders because they don't eat what we want them to eat. For example, mud snakes are great feeders in captivity. If they are properly caged, they will readily take appropriately sized Sirens and Amphiumas. But I wouldn't recommend one as a pet!
Gray-bands aren't bad feeders at all. They will readily accept small lizards as babies. A few individuals are picky about accepting mice, but most eat rodents readily.
Snakes that have been traumatized and possibly injured/parasitized during transport (= WC and farmed "CB" ball pythons) may not eat as they aren't healthy enough.
I haven't heard of a Pueblan being difficult to feed. They may be tough to start on pinkies once in a while, but the Pueblans I have had fed like pigs.
A baby cornsnake that isn't eating is probably looking for young anoles or small frogs. Try scenting pinkies and it should start eating.
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Chris Harrison
San Antonio, Texas