If the petsmart takes good care of them, then I don't see any issues there. I think with petsmart it really depends on the employees and how much they care for the animals. (I happen to work at a Petsmart and I know they care for the snakes as best they can). As for the snake not eating- sometimes they'll start eating if you give them live/pre-killed. I got my own bp from petsmart and she hadn't eaten for three weeks before I got her. I switched to prekilled and now she has a fantastic appetite and will eat anything and everything I give her. Some snakes just don't like frozen.
One thing you could try, depending on how long you're in the area- Petsmart has a 14 day guarantee. Get the snake, keep it for a week or so then try feeding it. If it still doesn't eat, return it.
Also: Petsmart is not Petco. I've had way too many animals die of disease from Petco. Petsmart tries really hard to treat sick animals, not sell them.