It's manly and they can grow a good thick one.
Well, I don't KNOW, but when I was sent to Saudi in Desert Storm, one of the early items that the First Sergeant quietly told the guys were told to do was to grow a mustache. Now, it was one of those uncomfortable issues that does not not get talked about a lot, but according to what I was told, a fair number of Saudi Males are - ahem - "Bi" - and a clean shaven adult male is sending the signal that he is a "receiver", if you catch my meaning. I would have laughed it off, except for some odd incidents we ran into when we tried to go into town. The only explanation that seemed to fit the observed facts was that, yes, the First Sergeant was correct, because none of the Saudis were trying to hit on the American guys with Moustaches. The clean shaven guys, on the other hand, seemed to be REAL popular, if you get my meaning. You are welcome to take that for what it is worth, but that is what it sure seemed like to me. I have been back to the Middle East multiple times, and noticed the same phenomenon.
It could have all been some kind of strange cultural misunderstanding, but I know we all got along a lot better with the locals after the American guys all grew moustaches.
i doubt there is any maybe coincidence
Just to irritate you? Never heard of any religious reason for Muslims to have facial hair, but I'm not really that up on the subject. Maybe it's just a style thing?
The Jewish, Amish, and I thin Russian Orthodox have had rules like that, just never ran across it in my limited readings about Islam.
to hide the sweat when they are lying, like the police.