I work at a petsmart (actually, I'll only be working there until sunday). Really, my only complaint is that they don't take enough time choosing new employees.
Petsmart is setup for success. They have the stars aligned for great animal husbandry, however it's all in the hands of the employees. Some of my fellow employees are well-educated about animals (I'm the reptile 'expert' there), and one is actually a Vet-tech. We do a lot for the animals, but every once in a while someone slips through that just absolutely sucks. You know the type. They don't have any clue what they're talking about, and they take shortcuts when it comes to giving proper care.
Other than the employees, petsmart stores work with qualified vets to ensure that their animals are healthy before being shipped to stores, and they also provide veterinary treatment for any animals that are sick while they are in the stores (even if it means dropping $100 to help a $9 hamster). But, like I said before, it's all about the employees. If the managers just don't care enough, they won't take the animals to the vet. All sick animals are also isolated from healthy ones, and the quarantine procedures are strict, so long as the managers enforce them.
So don't blame the company, because I've worked there for long enough to know that the company cares about the animals. Blame the managers and the employees they hire. But let's face it, for $7 an hour it's hard to find qualified help. But take it from me, the procedures that petsmart sets forth are second to none. Also, contrary to popular belief, the company does not force stores to keep reptiles on calcisand or other potentially harmful substrates. In fact, the care books they provide the stores with say that calcium sand should NOT be used with anything other than adult animals for risk of impaction.
So just make sure the blame is placed where it should be, on incompetent managers. They have overall the most control over the health of the animals in their stores.
Also, I have talked with people at petco, and though it is not always abided by, there is a rule that says that they can ONLY feed frozen rodents to their reptiles, which means that a finicky snake like a young ball python will have a tough time indeed. Especially if the managers actually follow that rule. In that case, I wouldn't really be too suprised about the death of a ball python in one of their stores, but I also have recently come to believe that reptiles should not be sold in ANY pet stores. They are much more a hobby than a pet, and I think their sale should be limited to reptile specific shops. But that's just my opinion. Like I said, I've worked at one of the largest chains of petshops in the country, and I've also been to countless 'ma and pop' petshops, and it just doesn't appear as though a 'petshop' setting is suitable for reptiles.