All these whackaloons who are calling for, "can we just start profiling now" are your basic, "Why can't we just be racist like we used to be," types. No. Shut up. They are.
Why? What does a Muslim look like? No, I'm serious. Do you think they get it tattooed on their foreheads? I've known followers of Islam who were more bunt-cake, flour-white, suburban kids than Bill O'Reilly (which, since we're profiling here, put down the whiskey, Bill, get back to work, don't give the Irish a bad name, again, and disavow your IRA ties now, before we come for you). Are we going to make them wear yellow crescent-moons sewn into their garments so we can tell them apart from the other God-fearin' 'Mericans (50 extra bonus points if you get the Godwin reference here)? Are we going to profile "araby types" because that would have missed Umar Abdulmutallab who is a black Nigerian (a little too swarthy if you get my meaning). It also would have missed Richard Reed, the other "I've got a bomb in my clothes for you, baby" guy. Are we going to get sly TSA officials to ask the questions when you go through port control like the bridge guardian in Monty Python's Holy Grail.
"Those who wish to cross the TSA line of demarcation must answer me these questions three, 'ere the boarding area they see. What is your name?"
"What is your quest?"
"To destroy the imperial west."
"Are you a radical muslim?"
"No. I mean, yes. ARGH!"
Really. If it's not racism, I can't figure out what it would be. Because the only other answer is that these people, who hold positions of some prominence, are clinically brain dead.
Think profiling will stop the terrorists? Nope. John Walker Lindh. Remember him? The American Taliban. Probably as white-bread as you can get. Timothy McVeigh? The other white meat. As Wednesday said in the movie The Adams Family when asked what her costume was supposed to be, "I'm a serial killer, we look just like everybody else."
Now, there are some ways, but they're not fool-proof. If you're highly trained enough you might be able to spot some tell-tales. I usually can spot someone who has been in the military from the way they walk (well, that and their clothes, etc). I can even make a reasonable guess at the branch and relative rank. But here's the thing, since I know what I'm looking for, in my own case, I intentionally break all those tell-tales. No b-line on me buddy boy. No precision in step. Nothing to really give me away. And that's the problem. You can train against that kind of screening.
Back-scatter x-rays? There's these things called body cavities. You can hide some interesting things in them (ask your local prison inmate or drug mule). Poof machines? Worked well in the lab, but strangely enough when in the real world with real conditions such as air movement from HVAC systems and the perfumes and other things normal people wear, not so well. Maybe if they pray at the airport with prayer rugs? Hey, remember the 9-11 report that talked about the guys being instructed to go to strip-clubs to throw off suspicion? And if all that remains is pulling people over for having scraggly beards, whell, there's a Gillete razor for that.
Nothing is fool proof. As we used to say, we have to be lucky 100% of the time, the terrorists only have to be lucky once. Terrorists, they're the new Red Scare Communists. Get 'em while they're hot.