Mitt Romney, the leading contender to become President Obama’s Republican opponent next year, had just finished working the room at Blake’s Creamery here when he paused for a photo with the restaurant’s owner, Ann Mirageas, and decided to tell her a joke. “I saw the young man over there with eggs Benedict, with hollandaise sauce,” he said. “And I was going to suggest to you that you serve your eggs with hollandaise sauce in hubcaps. Because there’s no plates like chrome for the hollandaise.” The proprietor laughed weakly. “Good luck to you,” Mirageas said. The hubcap joke must have killed...