I have J-Dar too, I'm not 100 per cent at it, more like 90.
Someone mentioned a Kingdom smile, i call it the Jesus/cult smile, after you talk to some for a while they usually have that Jesus smile on their face, and it's not just JWs, any other Cult, like the one the Duggars belong to and many others. After I've heard some folks in other folks talk and they tell a story and then Jesus comes into it they usually have that smile on their face.