I have yet to do any shows. But I can tell you that I don't feel comfortable letting go of any animal that hasn't eaten at least 3-5 times.
Since its my name and my reputation going with that animal I want to make sure that the buyer gets the best animal they can get. This means that they get a healthy, visualy apealing, animal with a good feeding responce.
IMHO it speaks better of the breeder to tell customers..I want to make sure my animals are the best I can sale, even if it means I may lose a sale because I don't have something available right then.