No, but I nailed a friend of mine because he didn't tell me he carried into my house. I saw it print when we were taking gun cases out of his trunk. But he failed to tell me. He got embarrassed when I pointed out that he is supposed to disclose that.
I made it up to him by putting his Mini-14 back together (first time I've ever touched one) and telling him that I'll help him sight in his rifle next time we go out to the range.
I see people carrying all the time. A lot of military in the area.
The biggest 'tell' for someone carrying is the oversized belt and constantly, subtly adjusting it. If someone has a big bulge around their waist that they brush against a few times a minute... watch for it and they will imprint. I seem to recall saying that.
The only time I was ever bothered was standing at the sporting goods counter at China-Mart during the recent ammo shortage. When he pulled his wallet out, his shirt hung up on his gun and I had to tell him several times that he was clearly showing. It was like I was speaking Swahili to him.
My kids can spot them fairly well. I think it has to something to do with the fact that a lot of them are at eye level to them. My son just pokes me and then points on the sly. He thinks it's a great game.
Oh, and at the gun show the other day I stopped counting.