Exactly what I was thinking. It's not that snake oil sales people sold totally useless stuff, its just that the stuff they sold did not deliver the value that was promised. Another example that is still going on today. There is a community of people that swear the ingesting silver prevents all kinds of things, even so far as a cure for cancer. It's snake oil, but it doesn't mean it doesn't have any medicinal purposes. Silver does have anti-microbial properties and can be used topically to manage infections.