Hmm… Not all Catholics go to Ash Wednesday services (it’s not obligated, and I happen to consider it counter to scripture), many churches nowadays don’t care about women’s headgear, and you can usually identify priests and brothers of different orders by their garb, as well as nuns-- brown robes with rope belt = Franciscan, for instance. And the folks at the airport in the saffron robes are Hare Krishnas, basically a sect of Hinduism. They may look freaky, and I’d never convert, personally, but they’re harmless-- Probably safer than the folks in business suits at the airport, in fact.
I hung around them a lot back in the 1970s. (For the free food; didn’t care for their religion.) The chief danger with them is they may bore you to death.
But they’ve been involved in their share of skullduggery! See the muckraking book Monkey on a Stick for some nefarious examples.
As to how this relates to the OP, watch out. A lot of them while hawking books on the street will dress in civvies and not reveal their organization, but you can always spot them by the bad wigs they use to disguise their bald heads. And by their slightly robotic manner of speaking.
A person standing in a public area wearing a big pocketbook and not preacing out loud–**that’s **a Jehovah’s Witness.
A group of people wearing the same suits and a fez-es on top–Shriners.
A woman with her head and face covered–Muslim for the most part.
A woman with just her head covered in a shawl–might be Hindu.