Your point about the fallibility of self-reporting sense of smell is valid, but please don't talk about real and serious food sensitivities in such a flippant way. They aren't subjective in the same way as smell, and there are medical tests available and widely used to verify intolerances (such as the hydrogen breath test for lactose intolerance, or the intestinal biopsy for Celiac disease).
For testing by sense of smell to work with any degree of certainty, there would have to be similar tests beyond self-reporting.
For testing by sense of smell to work with any degree of certainty, there would have to be similar tests beyond self-reporting.