This is NOT a marketing ploy to encourage you to throw away perfectly good food so that you'll spend more on groceries. Perhaps you'd benefit by having a calendar in your kitchen. When something starts pecking its way out of the shell, the egg is probably past its prime.
Milk is spoiled when it starts to look like yogurt.
Yogurt is spoiled when it starts to look like cottage cheese. Cottage cheese is spoiled when it starts to look like regular cheese. Regular cheese is nothing but spoiled milk anyway and can't get any more spoiled than it is already. If opening the refrigerator door causes stray animals from a three- block radius to congregate outside your house, the meat is spoiled. Fuzzy and hairy looking white or green growth areas are a good indication that your bread has turned into a pharmaceutical laboratory experiment.