Milk

"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. Cheddar cheese is spoiled when you think it is blue cheese."
Nice sentence or two from Will Work For Food, in response to best when used by.com. Its a funny little site that lets you enter all the best before dates of your food, then emails you the day before its due to be chucked. Pretty time wasting and useless if you ask me. The old sniff test has never failed us.