I hear where you coming from Fay and sometimes it is the animal but more often it is the breeder/seller of these animals.
2 years ago I bought a 1year old diamond python from a highly reputable breeder, very well know over here. Anyway, the animal was no bigger than a hatchling and when I received the feeding record this poor animal had received only 3 small meals in the previous year. Just the seller trying not to spend too much of his profits on the animals they are trying to sell. Thankfully there are not too many breeders out there like this one.