I was able to briefly study a group of marbles that came from a dump in Shanghai. And I can't swear to it, but the way I recall it, all of the swirls when the "wrong" way. (There were more in addition to these, but I don't have as clear of pix of them. Still I think all went the wrong way.) Never learned whether it was a generic garbage dump or a glass factory dump but this is the main inspiration of my idea that maybe in China they had operations set up opposite of how Americans did it.