Is the "ugly produce'" trend already reaching the end of its shelf life in supermarkets?Walmart and Whole Foods in recent years tried selling some blemished fruits and vegetables at a discount, produce they said might otherwise be trashed because it's not quite the right size, shape or color. But the two chains and others quietly ended their tests, suggesting dented apples and undersized potatoes may not be all that appealing in stores where better looking fruits and vegetables are on display."Customers didn't accept it as much as we had hoped," said Mona Golub of Price Chopper, a grocery chain in the Northeast that also discontinued its offering of ugly produce.