The easy stuff is in unmolested, original packaging that simply arrived at it's "due date". You can hardly go wrong there. I just scored several packages of brats. Packing intact? Check. Pass the visual? Check. Pass the smell test? Check. Heat one up and try it? Passed.
Gas station/convenience stores are the worst (best?). They have all these individually packaged sandwiches and whatnot, and when they hit date into the dumpster they go.