Should you correct others' mistakes?

Here's a question to ponder: If a retail store makes a mistake in your favor, do you correct the cashier, or walk away with the savings?


Today I walked away with $11 more than I should have. I ended up having to return the items I bought on Friday at Walgreen's. That transaction had been so confusing, the manager had a hard time understanding the receipt. So I pointed to each item and explained: full price for this one ($21.99 minus $3 coupon); half off for this ($9.99); and a coupon gave me the refill pack free.


I should have gotten $31.38 back, after sales tax. But I walked away with $42.20. The manager refunded me the cost of the refill pack, plus the full $21.99. I guess he didn't see the coupon that was used further down the receipt.


Point is, I profited off this employee's mistake. But I also purposefully tried to explain the situation to him. He did not ask me to repeat it; and apparently he wasn't listening all that carefully the first time.


Was I wrong to take the money? Should I have attempted to explain the situation again when I heard the wrong amount? Or was the onus on the employee to listen better?


My own conscience is a little troubled on this one. I think, normally, I wouldn't have accepted the extra amount. But I was tired. And annoyed that he hadn't listened to me. (He nodded while I talked, but he did not take his eyes off the receipt.) Still, it probably wasn't right.


What would you guys have done? Are these situations black and white? Or are there shades of gray? In other words, are there conditions when you would say yes and others when you'd say no?


For example, I correct cashiers who give me the wrong change. I don't want the person getting in trouble for the till being off. But when it's a case of the employee ringing up the wrong price (in my favor) I don't say anything.


Why this distinction? I have no idea. I guess I was raised to believe that it's the company's duty to make sure its employees are capable. If it doesn't properly train and supervise its employees, the company has bigger problems than one wrong transaction.


Of course, following that logic, I shouldn't correct the cashier if I am given too much change. It's just another case of an employee mistake. But it's harder to rationalize that because I've been a cashier before, and it completely sucks to be missing money at the end of the day.


I am sure there are plenty of people who will argue that it is never fair to take more than what you are owed. In theory, I agree with this. After all, I always make a fuss when an item rings up higher than it should. So why should I stay quiet when the error is in my favor?


However, theory and practice are two different things. I'm not necessarily proud of my behavior, but I cannot think of a single time I have corrected a cashier about an item being too cheap.


So what's your take on this? When would you be okay getting an error in your favor? When would you speak up?