FRANKFURT — Art exhibitions can grow out of long-nourished ambitions or sudden inspiration. "Dream Factory Communism," a show of Stalin-era works at the Schirn Art Gallery here, grew out of a taxi ride. In October 2001 the gallery's director, Max Hollein, flew to Moscow to plan an exhibition of works by Wassily Kandinsky. On his way from the airport, Mr. Hollein recalled recently, he was fascinated by the strange mix of billboards along the highway. Some were Western-style advertisements for Coca-Cola, Levi's and other global brands. Other ads for Russian vodka, beer and the like echoed the Socialist Realism of...