In the 35+ years I've been carrying, I've been "made" twice. Sort of funny, for both times took place in my local 7-11 store!
The first was back in about 1974, when I bought my home. I was taking late night walks around the neighborhood, looking at the way other folks had remodelled or "fixed up" their homes. I decided to walk over to the local 7-11 store for a cup of coffee.
As I approached the store, the employee was outside, sweeping the parking lot. A sudden gust of wind flapped my windbreaker, exposing my handgun. I immediately explained to the store employee that I was a LEO. His response was, "You look like a cop!" (BTW, he eventually became a LEO).
The second time was also for a cup of coffee at the local 7-11 store. I thought that I had discretely removed my wallet from the rear pocket of my trousers without exposing my handgun, but my jacket must have snagged. While standing in line to pay for my coffee, the customer behind me stated, "Your 'roscoe' is showing!" I turned toward the voice, and there was a clean-cut black man, in his mid-20's. I immediately told him that I was a police officer, and he merely nodded his head. I asked him if he was a LEO (he looked like one!), but he replied with, "No, but I'm glad that YOU are a police officer!"
Both of those incidents took place in the early 1970's. Since then, I've become more "savvy" about carrying. IWB holsters are the best, and learning how to utilize body positioning helps a lot. I haven't been "made" since about 1975.