Why would anyone really care if it's paints or anything like that though? Of course the metallic bits in car paint are glitter, what else would they be? It seems like it could be government related, like money or military use as some sort of anti-radar chaff, but both of those seem like they fall afoul of "you wouldn't know it's glitter looking at it". So I'm going to guess it's either something ingestible like toothpaste (though could they get that past the FDA without having to label it?) or it's some luxury product where gold or gemstones are being punched up with glitter and they don't want you to know.
