The Miracle Salve owners should have sent the Miracle Salve to Dr. Pendyke, the veterinarian, rather than Opie Taylor Sr. Dr. Pendyke is the one who wanted to resell the product and Opie Taylor Sr was a consumer.
Aunt Bee should never have accepted a delivery of this size and cost and for an unknown person such as "Opie Taylor Senior" without first calling Andy at work.
The stacks of Miracle Salve boxes sent to Andy's house would not actually be that big of a problem. Since no contracts were signed and no money changed hands, all Andy would need to do is store the boxes in his garage and wait for the salve people to come looking for their money, then just tell them to haul it away.