buck00 is absolutely right in his writeup.
I worked undercover in the absolutely worst parts of our city. When I walked down the street, the Locals could tell that I was not indigenous to the neighborhood, and so some would start "sizing me up" as a potential target.
However, I would immediately take a tactical assessment of them as a threat. I would first scan them head-to toe, then special check at their waistband, pocket, then the armpit.
Then I would watch their eyes, hands, & body language, then find a point of aim on the upper-hydraulics & upper central nervous system area of the potential threat.
And, of course, I had my jacket open, so that I could access my pistol immediately.
It's a funny thing. Although those folks sizing me up didn't know WHAT I was doing, they knew that I wasn't acting like food. In fact, they sensed that I was assessing THEM as food, & they didn't like it one bit.
They normally got nervous and gave me a wide birth (probably believing that I was crazy, dangerous, or possibly both).
In 23 years, I only had 1 challenge me, & he was a drug dealer that thought that I was trying to invade his turf.
