Kevin,
Your explanation is flawed owing to what I believe might be a less than complete grasp of accounting.

The points I made are still totally valid and not remotely repudiated or proven wrong by your example.
As a first step, it would help your understanding to be able to differentiate between cost of sales and selling expenses.

The only way that your idea/ theory  would make sense is if the supermarket was to fail to account properly for the rebate / payment of the selling expenses (advertising and promotion) in contravention of GAAP, IFRS, plus various statutes. There is no evidence that this is the case - such action would be reckless and stupid in the extreme.

Which brings us back to the external independent auditors.........................