Originally Posted by
manneca
Well, a good Muslim would probably be able to determine at a glance whether you were a practicing Muslim. And s/he would definitely know at an instant whether I was or not. I can tell if someone is a Hasidic Jew fairly easily. I can also tell if someone is Amish or Mennonite (though there are some Mennonite sects I can't tell).
Hmmm... I think it'd be hard to tell at a glance when it comes to men. Women are a bit easier to guess due to the practice of covering the hair/head, but even that is interpreted in starkly different ways by different women in different sects in different places. I had to ask my wife whether something worn on the head of a Kuwaiti lady I'd photographed in Rome was for religious purposes, and she said that no, it was just holding her hair in place!