There are a few fanny packs that are specifically made for CCW, pull strings both on one side, logo front and center, etc. Another tip is the way they are carried, wearer is constantly figiting with the heavy block of steel trying to get it intoa comfortable postition or back where he wants it because the weight shifts. One guy in particular was the husband of my wifes friend. They came over to our house for a meet & greet type event and he had a large pack that seemed out of place. I figured that it contained a gun but didn't really care. Some time later we actually started talking gun and he announced (proudly) that he had a gun right then. I told him I pretty well knew and that somewhat deflated him.
I don't think that being on this forum has led me to 'spot' a CCW, but being aware of what a CCW fanny pack looks like has. If I didn't peruse the shops that sell such things I never would be able to recognize them. No big deal, 90% of the population still won't recognize them and that's fine.
In truth, I think this is kind of stupid. I don't care who carries but when I see a pack to me it's noticable. I use a fanny pack in the mountains and on my bike at times, but when you see a 20-30-something white guy continually fussing with a large fanny pack worn in front, that's just not 100% normal. Big fricking deal.