I just had strawberry ice cream that didn't taste anything like ice cream made with real strawberries. In some cases, some of these chemical flavorings do a decent job, but in other cases they are way off. I think that jelly beans are a great example. 1000 chemical flavors, no real foods used.
What things have you had where the flavor was way off or a situation where the real food wasn't there but the flavor was perfect.