I know exactly how you feel, I see that stuff a lot at pet shops around here.

Now, if you were to save and go back to get the snake, it could either help or harm the situation.

Harm: you could get a snake that is very ill, so expensive vet bills, or you could be just opening up a spot for them to bring in another snake and not keep it properly.

The way you could make it help though is if you maybe try to talk to the person in charge at the store, let them know that they aren't doing things right and that anybody who knows about keeping reptiles can clearly see that. See how they react, and go back later to see if they made any improvements, and if they did, buy the snake. If they didn't, you could maybe try contacting authorities about it (what I'm planning on doing for a reptile zoo this summer).