A Jihad Watch reader once wrote:
"Muslim beards are ideal for keeping an eye on these brainless twats- subversive thugs who advertise their identity."
That would only work if all Muslims who kill, or plot to kill, have beards.
Hasan, the Fort Hood shooter, himself didn't have a beard when he killed 13 (+ 1) and was fully intent on killing dozens more if he could, until he was stopped by a bullet. If he could, he would have mass-murdered not just dozens, but hundreds, thousands, millions. He just didn't have the materiel to do so -- but the fanatical murderous intent was more than loaded and ready.
Actually, there is no marker we can use (in the absence, of course, of positive intel which we will not always have 100% of the time with 100% accuracy, thus forcing us to use whatever else we can to save lives before an attack) -- other than racial physiognomy which, while not perfect, is certainly better than pretending that all of Mankind is one undifferentiated mass of tapioca-colored humanity and pretending that most Muslims are not ethnic-looking.
A certain reader of my blog a couple of years ago took me to task (also see this essay) for advocating racial profiling as one technique (not the only one) in our ongoing need for Muslim profiling -- then this same reader, claiming to have sophisticated knowledge of various cultures and ethnicities, turned around and criticized me for not being able to tell that Cat Stevens is of Cypriot extraction, rather than Greek extraction (as I had written). I answered him back that if there are people as smart as he is, who can discern the subtle granular differences between a Cypriot and a Greek, then surely we could employ people like him to help us tell who is -- to pluck one example out of hundreds we could pick from a keffiyeh -- a Libyan and who is an Italian (one of the many fine ethnic distinctions I would be utterly incapable of making: heck, I usually can't tell the difference between a Mexican and an Arab, if there were a room full of both).
But if there are people who can tell these differences, then obviously an ethnic profiling can be used to help us identify possible Muslims -- and we should avail ourselves of every technique we can, no matter how potentially imperfect it may be. Nothing in life is perfect. We surely don't want that as a motto after another successful 911 attack (let alone another Fort Hood attack), do we?
I've written quite a few essays here over the years that tackle this subject from various angles. See this Google page for several (if not all) of them.