For months now, every time I wear my 'decent' black shoes, I've noticed some white spots about the size of a match-head on them.
It rubs off easily enough, but sometimes I forget to check and end up going to a meeting with spotty shoes.
The spots seemed to appear as if by magic, even if I'd polished the shoes the night before.
I couldn't fathom it. Could it be pollen from the clover flowers, picked up as I walk across the lawn? Was it some form of mould that thrived in the dark of the shoe cupboard? Volcanic ash perhaps...?
Today I finally sussed it.
I really have to stop walking around and talking while I'm cleaning my teeth.