Toothpaste colour-coded for toxicity an urban myth

A friend at a dinner party recently regaled us with horror stories about the toxic nature of toothpastes. She even brought us an approved, "natural" toothpaste, apparently available only in Chinese supermarkets and pharmacies, which was very nice of her (it tastes OK, and feels like normal toothpaste, although I have no idea if it will actually clean my teeth).
She also pointed out the small coloured squares on the crimp at the bottom of all toothpaste tubes, which she insisted are an industry colour-coded guide to the relative toxicity of different brands, black being the worst, and green being the most benign. We were skeptical about this and, after a little bit of research, it seems we were right to be skeptical.
Toothpaste probably does contain ingredients that are, to some degree or other, harmful. But it turns out that those coloured squares on toothpaste tubes are nothing to do with the chemical content of the toothpaste within. They are actually whatever known in the packaging industry as "eye marks" or "colour marks", and are used to indicate to the automated packaging machinery where a package is to be cut or folded. The different colours merely signify different types of packaging or sensors. Thank you Snopes.
Whether you see colour-coded toothpaste as an unfortunate misconception, a popular urban myth, or a highly successful Internet scam, probably depends on how generous you are feeling. It does seem, though, that some producers are taking deliberate advantage of the erroneous "secret knowledge" about toxic toothpastes being widely disseminated on the Internet. Ah, that old Internet thing...