On Thursday, 3 June 2021 at 15:03:45 UTC+1, Tim+ wrote:

There are some folk who genuinely cant smell the stenching agent (like the
way some folk cant smell asparagus in their urine).

I think age also comes into it. Older folk generally have a poorer sense of
smell.

Tim


Not just older people. One of the hallmark symptoms of Covid-19 is anosmia. And that can last at least months after the acute phase - indeed, I am not sure whether it might be permanent in some.