They get it wrong, you get it free

B.F., a reader who lives just outside of Columbus, Ohio, has a disagreement with his wife. He has encountered "a pricing situation" at his grocery store.
The story offers a scan guarantee. If an item scans at the cash register for a different price than what is displayed on the shelf, the item is free as long as it doesn't cost more than $5.
As a "frugal customer," B.F. pays close attention to the prices of groceries when he and his wife shop. After benefiting from one of these scanning mistakes, his casher remarked: "We left last week's sales price up." But the price that scanned had reverted to the non-sales price. The cashier honored the guarantee and gave B.F. the item without charge.
Since that incident, B.F. has noticed that the sales prices listed on the shelves include in small print the date of expiration on them. "These signs with the sales price are almost always taken down after the expiration date," he writes.
Typically, because of his frugality, when B.F. is searching for a particular grocery item that has several variations or brands, he almost always picks the cheapest item. But since that first scan-wrong-and-get-it-free encounter, he now looks for items that had old sales tags up on the shelf. He verifies that they are old and are likely to scan at a higher price than the sales price posted by looking at the expiration date on the signs.
"I pick this item, even though it is not always the cheapest price, knowing I will get it for free under the store's guarantee," he writes. "I do not stock up on these items, nor do I deliberately seek out free items that I wouldn't have purchased anyway."
B.F.'s wife believes it is unethical for him to purchase these particular brands knowing that they will be free, if he would have otherwise made another choice based on the displayed price. But B.F. believes that this is part of the reason the policy is in place. "The store is, in effect, compensating me a few dollars' worth of free groceries for alerting it to its mistake, which it can then fix for future consumers," he writes, asking: "What is the right thing?"
Technically, I suppose, the store has a legal right to claim that by posting the expiration date on the sales signs, it is not obligated to pay out on these items that have reverted to their pre-sale prices. But the spirit of the scan guarantee seems to suggest that if any pricing sign is up and wrong, regardless of the small print, then it will honor the guarantee.
Even though he claims not to go looking for free items that he wouldn't have been purchasing anyway, I'm not convinced this matters. His attempt to avail himself of the guarantee doesn't strike me as somehow being sullied by premeditated attempts to scope out wayward sales signs that should have been taken down when the sale ended. If the store didn't want customers like B.F. to figure out how to score some free less-than-$5 groceries, it shouldn't have set up the guarantee in the first place.
The right thing is for the store to do a better job of keeping its signage current and to honor its guarantee for as long as it is in place. 
Jeffrey L. Seglin, author of The Right Thing: Conscience, Profit and Personal Responsibility in Today's Business and The Good, the Bad, and Your Business: Choosing Right When Ethical Dilemmas Pull You Apart, is a lecturer in public policy and director of the communications program at Harvard's Kennedy School . 
Follow him on Twitter: @jseglinhttps://twitter.com/jseglin 
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(c) 2013 JEFFREY L. SEGLIN. Distributed by Tribune MediaServices, Inc.