I was talking to a non-paleo friend who said that grocery stores tend to repackage or regrind their expired meat with fresh meat, add more C02 to make it look red again, and then put it back on the shelf with a new expiration date until it sells. Is that true? Do all grocers do it?
I had assumed sell-by dates would be regulated by the USDA or something, but apparently not.
Obviously just-killed, properly-handled, direct-from-farmer-you-trust meat is the ideal, but I know a lot of paleo folks eat meat from the grocery or local butcher too. Have you seen any data that could help quantify the risk of consuming potentially old meat?
(Here is a list of common bacterial nasties, some of which grow under refrigeration and/or leave toxins that aren't destroyed by cooking... probably not good to consume even if you don't get acutely ill)