Dairy products: Ice-creams & yoghurts
Ice-creams: Mostly all ice-creams are made up of doubled cream milk therefore they have shorter life than any other food product. So if you notice that your ice-cream has turned darker or it tastes like cream cheese than it's time to bin it.
Yoghurts: If it looks clean and fresh that means it is, because it goes under preservation method, lactic fermentation process. But if you notice moulds of any colour you better know what to do.