Mobe613:
This often happens when young men (or men of any age really) go out in public places that are outside of where frum yiddin usually are . . . usually this is also accompanied by wearing clothes that are not usually worn by bnei torah at home (ie like khaki pants or a tshirt/polo shirt.)
You must not know many bnei Torah. I know many, many, many, bnei Torah who wear khaki pants and polo shirts, not only at home, but also to work and (gasp!) even to daven.