In 1893 Clark Stanley wowed his audience at the World’s Colombian Exposition when he pulled a rattlesnake from a sack, slit it lengthwise, and dropped it into a large pot of boiling water. When the fat bubbled to the top, Stanley bottled it and sold it to members of the awed audience as a cure-all.

In 1916, after Stanley had made a fortune from sales of Stanley’s Snake Oil, the US government examined the product and discovered it didn’t contain any snake fat at all. It contained fat, yes, but only one percent, and beef fat at that. Thus today’s common usage of “snake oil” to refer to a worthless product with fraudulent marketing claims.

But here’s the thing: Stanley’s rattlesnake oil was inspired a practice in ancient Chinese folk medicine whereby water snake fat was used as a salve for arthritis and skin irritation—an effective treatment due to the high omega-3 content of Chinese water snake fat (20 percent, compared to salmon’s 18 percent and the rattlesnake’s mere 8 percent), which has been shown since the 1980s to reduce inflammation.

So the next time someone tries to sell you snake oil, they might genuinely be trying to sell you snake oil. Or it could all just be beef tallow mixed with water. It’s up to you to do the research and determine which.

(Stanley, by the way, was fined $20 for his deception.)