Most of us learned in high school biology class what were good media for growing bacteria cultures. OR have learned what food prep services harbor bacteria or do not.
The fabric of your typical mask combined with a constant supply of warm moist air plus darkness (face side) is “happy land” for bactetia.
Note “bactetia” is a new variant of bacteria. :)
Which is why I basically refused to don the diapers.
For a year now I have thought masks are just a way to make sure people GET covid.