Mr. Adams said on Tuesday that he needed to be on the ground at the World Cup this year, rather than send an aide in his place, for the same reason he occasionally rides the subway and visits homeless shelters. “I go on the ground to observe,” he said. “You have to be on the ground to see what’s going on.” For Mr. Adams, the trip satisfies one of his peripheral passions. As Brooklyn borough president, he traveled to places like Turkey, China, and Azerbaijan; as a state senator, he drew unwelcome attention for a trip to South Korea. As...