Finding bad food in the store

You're definitely not the only one.  Grocery stores far and wide all invariably have food out that is past its sell-by date, has expired, and with produce you can surely find mold here and there.  With the moldy fruit, usually what they do is cut around the moldy part and put the rest of it in a pre-cut fruit cup or something like that.  With the expired meats and products, sure they'll take it and act apologetic but after you leave, they'll likely put it back. They don't all do that, but most of them do.