There have been some calls for Muslim men to be subject to extra scrutiny when boarding an airplane. Morality aside, this simply is not an effective strategy for detecting or deterring potential terrorists. How do you tell if someone is Muslim?
You could ask them, since most Muslims are quite open about their faith. But I would suspect that a Muslim with hostile intentions would lie about his faith to avoid increased scrutiny.
Skin color is a poor indicator, since there are black, white, and Asian Muslims.
In India, if a male body goes unclaimed, it is given a Muslim burial if the penis is circumcised and Hindu cremation if it has not been cut. Of course this method of determining someone's religious faith would be ineffective in the US.
Putting in a policy that subjects Muslims to additional scrutiny would only serve to alienate peace-loving Muslims.