I don't go to Petco any more, ever since finding out that their bosses /especially/ don't care about the livestock. I mean, chain pet stores are in it for the money, but Petco seems especially bad. I saw a tank of juvenile dart frogs, which are tiny, being kept with crickets over pinhead size. Not only were the frogs too small to eat the crickets, but the crickets were large enough to threaten them. When I mentioned this to an employee, she told me that corporate hadn't sent any appropriate food (fruit flies), even though Petco often stocks that appropriate food. They also hadn't provided any care information for the dart frogs, even for the employees to use. Petco corporate treats animals like inanimate objects, not like something that deserves the basic respect of being properly fed.
That said, the knowledge and commitment of individual employees can be a game-changer for individual stores, and they do sometimes have some good stuff in.