(AFP) – Ever paid top dollar for a bottle of wine that says on the label it's from a much-sought-after year, only to find that it tasted like cheap, non-vintage plonk? Well, a team of researchers in Australia, who think "vintage fraud" is widespread, have come up with a test that uses radioactive carbon isotopes left in the atmosphere by atomic bomb tests last century and a method used to date prehistoric objects to determine what year a wine comes from, or its vintage. The test works by comparing the amount of carbon-12 and carbon-14 in grapes.