I profile on both appearance and actions.
I can think of two cases in particular, years apart, and in each I was taking my mother out on her birthday.
In the first, we were on a skywalk in downtown St. Paul and we both saw a young black male watching us without being seen to be watching us . . . my mother shifted her purse to the other shoulder, and I put myself between her and him. He rolled his eyes with an expression like "Oh, crap, they made me" and walked down a nearby stairway. There's NO DOUBT he was weighing his chances of snatching her purse and outrunning me afterwards.
In another, more recent incident, we parked near a restaurant, and a couple of scruffy white guys, sitting in the parking lot, really looked us over . . . as we were getting out of the car, they walked by, really giving us the eye . . . and went around the back of another building. Less than 30 seconds later, they reappeared, and seemed very surprised, and, dare I say, disappointed - to see us still by the car. (BTW, good thing about pocket carry - you can stand there, hand on gun, and nobody sees anything but a guy casually standing with one hand in his pocket. But you're about 1/2 second away from BANG! if you have to shoot.) They then got back in their car, adjusted their mirrors, and watched us.
We left for another restaurant - they didn't follow.