Why not try to build a relationship with the people that work there? It wont always work but I walked in with Rainbow my retic and she grabbed their attention right away. Then spent some time talking to them about their husbandry after a few minuets of getting to know them. As a result my local Petco comes to me about care when they have questions and is very receptive to advice given. They don't mind when I do my shows if I direct people to better products than what they have in stock. They now care about the quality of care more than the bottom line.