I would have to say the only bad interaction, and it was a duzzie, was many years ago with a dorky little deputy sheriff in some tiny podunk town in upstate NY.
I was an active NYS peace officer at the time, and was caught speeding. No gripe there, I was speeding. At that time, the cops waited in their cars, and you walked over to them. I was carrying, and as a courtesy, mentioned I was. I didn't mention I was an officer. He gets out of his car and gets in my face, or as close as he could with about an 8" difference in our heights, and starts screaming with how dare I speed through his town (15 over on a limited access highway, NY RT 17), and why was I carrying a gun.
I worked in NYC, but as a state officer, the whole state was my jurisdiction and I explained that to him. He continues to scream at me. I ask him to stop, my wife and kids were in the car, and it was embarrassing. Finally I told him I wasn't going to listen to his crap anymore, if he wanted to write me a ticket go right ahead, and got back in my car.
He made me sit there for 15 minutes, and finally walks over, hands me back my license and registration, and without another word gets back in his car and drives away.
I was so furious I thought my head was going to explode, and told my wife I was going straight to his headquarters and filing a formal complaint. I had never been treated so disrespectfully by another officer. My wife calmed me down, and pointed out that despite his tirade, he hadn't issued me a summons. Just chalk it up to a bad experience, and go on. She also said who knows if his father (brother, uncle, etc.) wasn't the chief, because an officer with an attitude like that wouldn't last long otherwise.
I left it alone, but every time I think about it, like now, my blood pressure probably goes up 20 points.
And now retired after 40 years of service, I still inform an officer when stopped if I'm carrying. I do it for our mutual benefit. I don't want some nervous cop having a dangerous (to me) reaction if he sees a gun he wasn't expecting.