IN 1958, Sherman Adams, President Dwight Eisenhower's forceful chief of staff, was one of Washington's most influential men. His career, however, ended abruptly after he accepted an overcoat from a textile magnate under federal investigation. The gift might seem innocuous enough, but the coat in question was made of vicuña—an incredibly soft, light, rare and very expensive yarn. It was alleged that Mr. Adams, swayed by such luxurious gifts, subsequently tried to influence federal agencies on the magnate's behalf. Despite the politico's protestations of innocence, he resigned in a scandal that some dubbed the Vicuña Coat...