I actually took a couple of my permanent bumper stickers off due to what you warned about.
Twice, I had an old left wing hag stop her car behind my Bronco after I started to back up. The second time I had a disposable camera and took pictures of how she deliberately parked behind me in a blind spot. When she saw I was taking pictures, she drove off and gave the finger. The only thing that saved her was her age and she was driving a disabled driver vehicle. There were some other unpleasant events.