Incidentally, I disagree with the good colonel when he says that if you are armed, you "must be in yellow." I believe that's a generality that's quite situational, not an absolute.
While I agree with you, Pax, I did find out that in one instance where I felt safe being in condition white (on my Grandfather's farm, private land) I should not have been.
The only time that I have drawn my firearm on a person was after he tried to take my firearm out of my holster while I was saddling up a horse. Typically I carry a firearm out on the farm for protection from feral dogs and snakes, and I trusted this man (that I barely knew) because we had bought a horse from him (the one that I was saddling). Long story short, I learned the hard way not to trust too quickly; and to always be aware, the easiest time to be caught off guard is when you are just trying to do something relaxing.