I'm glad to get the input!

It is very tempting to do something when it "works" and it did work. The fact that the cereal coupon worked on cereal BARS was something I picked up on later, and it didn't really phase me, but I can see how others would think it wasn't right.

The part of my scenario that was bothering me afterward was the fact that they were expired by 10 days. It wasn't sitting well with me, and since it wouldn't sit well with anyone else here thus far, then there's my answer.