This is something that does tend to get heated since there are a lot of bad Petco stores out there. The one near my home isn't too bad from what I seen. Cages are very clean and the animals appear to be fed the correct diet. They don't always have the correct information about colors and good prices for their stock but they don't abuse the animals.
However, you need to use your judgement. Petco often imports animals that are wild caught (maybe not specifically corns but Balls and turtles)...are you okay with supporting that behavior? Many of us are not. Also, what are your intentions for the animal you are purchasing? If you want a pet quality snake Petco may be an alright option. If you ever want to breed the snake then I would suggest getting a snake from a breeder where you can see pics of the parents and know the lineage and history of health. Remember, petstores are where most breeders dump their animals that they can't sell to anyone else. I checked out some ghost corns (that were labeled as creamsicles way overpriced for either morph) at my local Petco and they all had spinal kinks. I hope that I helped a little, and good luck!
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Anna
The Zoo
Corns
1.0 Snow - Cornelius
1.1 Ghost(pastel) - Eek & Boo
0.1 Amel - Scarlet
0.1 Hypo - Nikko
0.1 Anery - Missy
0.1 Hypo Motley - Cordelia aka Cordy
Boas
0.1 Columbian (BCC) - Bella
Lizards
0.0.1 Leopard Gecko - Leo
Rats
0.1 Dumbo Agouti - Moon
1.0 Standard Black - Pluto
Cats
1.1 Siamese - Blue & Fiona
0.1 Gray DMS - Druscilla aka Dru
Horses
1.0 Thourghbred (Hunter/Jumper) - Morgan's Majesty aka Cody