“Seizing “Bird’s Nest” at Customs for its somberness was in line with the enforced beauty of the Beijing Olympic moment, which included putting a cute young girl with straight teeth on television while the public heard the voice of the actual gap-toothed singer of “Ode to the Motherland” at the opening ceremony. Yet the words in Mr. Zhang’s painting were surely a more acute problem for Chinese officials, and there were a lot of them.”