Getting back to legitimate responses (although the title is rather interesting...);
or that interferes with valve function; or
Any condition that interferes with the face-to-facepiece seal or valve function.
"Facial hair that comes between the sealing surface of the facepiece and the face"
To me, this says NO facial hair except for trimmed mustache. It seems that a goatee would interfere with the seal. Just because it happened to work at one fit test, possibly right after the goatee was carefully trimmed, what about in two days? The mask may not work. This is something officers have to crack down on right away, and not let anyone slide by. Hell, let the small goatee go, and what if the next guy shows up with a beard? Even over a small carefully trimmed beard, I bet you could pass a fit if you really tighten the straps. This doesn't mean it should be allowed.
I am not one big on lots of regulations and SOPs, but when they exist, they should be ENFORCED! Equally among people. Otherwise, change or get rid of them. We have a new guy, less than a year in, who is starting to grow a scruff on the end of his chin. He is a great guy, everyone likes him, but when I got in I was told nothing except for a small mustache.
One more thing to annoy me! lol