Independent presidential candidate Robert F. Kennedy Jr. once ate a dog — or so Vanity Fair wants you to believe. The magazine printed a photo of Mr. Kennedy with an unidentified female hamming it up for the camera on a purported trip in Korea, pretending to bite into a cooked animal. Vanity Fair says a veterinarian identified the barbequed carcass as a canine. Mr. Kennedy says it was a goat and that the picture was taken in Patagonia.  The allegation is just one shocking element in...