Grape, more than any other artificially created flavor lacks verisimilitude. It never tastes anything like grapes. It actually tastes like "purple". (Dave Chappelle's brilliant bit on grape drink (sugar, water, purple) touches on this.)
Two of my nieces both hate grape flavored things. They both say that it tastes like "medicine". My theory is that, in a beautiful irony, the attempt to use grape flavoring to make medicine appealing to children actually did more to destroy the appeal of grape flavoring in food products. Could the food manufacturing industry sue the pharmaceutical industry for destroying the equity of a flavor?