Xu Bing, a noted Chinese artist, has transformed trash in the most stunning and delightful ways at Mass MoCA. We go to the Massachusetts Museum of Contemporary Art in North Adams at least once a year, often bringing grandsons with us because there is always something weird and wonderful to see. I consider cigarettes, even unsmoked, as trash. For Xu Bing they are the raw materials of art. Xu Bing took this scroll as his inspiration, and…