Not really that unambiguous depending on the market and/or product. You could make the argument that these HIV drugs are miraculously helpful! As you jack up the price. People keep buying it at any price, must means its fantastically effective, right?
Even in less extreme cases, it may be just that you have extremely good salespeople / marketing team. With good enough sales, you can sell any kind of garbage, and in many markets it might be unlikely that complaints of existing users will reach or discourage new ones.
