Steve
Penultimate Amazing
I think that the high failure rates associated with masks are the result of people wearing them improperly. All the air one breathes in and out has to go through the mask for maximum protection. Duh. If you look at most people wearing the typical disposable masks (especially the flat kinds that wrap around one's face) there are large gaps at the sides around the nose and chin. Probably over 50% of the air they are breathing in or out is not being filtered. These simple masks can be fitted more effectively but it is difficult to adjust the fit and keep it adjusted correctly. The slightly fancier disposables, which come molded in a shape that better fits the nose, still have to be snugged down carefully to close a gap that typically forms between the nose and eyes.
There are much better that generate a tight fit and are far more effective. But these are much more expensive.
In general people also find masks uncomfortable and sweaty, particularly when fitted correctly, so they don't wear them all the times they should. And as discussed upthread, wearing a mask but not washing your hands is just silly.
Masks are completely useless for us bearded guys.