Snake oil is about the thing being sold, it's about the sales pitch. It's the people selling the product. An important snake oil trait is making grand claims w

Snake oil is about the thing being sold, it's about the sales pitch. It's the people selling the product. An important snake oil trait is making grand claims which have little basis as fact, particularly with things which are difficult to understand or difficult to verify (if not impossible.) You can say anything about a product if the prospective buyers can't verify the claims. And so, the claims tend to get broader and flashier. Therefore, a snake oil sales pitch could still be applied to a highly useful product.