"No, I did not wash the backs of the tiles, as they were random shaped and glued to a plastic mesh to facilitate the repeating 3 sq ft pattern."~~

About what you mentioned about ,the tiles are glued to a plastic mesh.I seldomly see the tiles be mounted on the mesh.I think there are many more difference between two countries.Is it useful for us to do that ?If the tiles are little one ,such as mosaic tiles.I think it will be impossible for us to do that . The same as ron said ,the chinese tiles are dusty and dirty.I think it is reasonable for him to say so .Are there many more difference among them?