I noticed that about 20 years ago, when I watched 2 or 3 episodes of COPS.
I thought that if they acted like that when they knew they were on camera, we wouldn't like seeing what they did off camera.
The only incident I remember from back then was an arrest warrant service in what I assume was a Section 8 townhouse complex. The actual arrest was smooth, the subject was cooperative and the police were polite. But the arrest proved upsetting for the arrestee's son, who vented his displeasure by riding his bike past the scene on the sidewalk (at least 50 feet from the cops) chanting taunts. (I don't recall what he said, but it was a little kid, about 8 years, and it was about as mature as "neener, neener, neener, piggies bit my weiner") When the kid turned around and went by again, two cops tackled him, knocking him off his bike and slamming him to the concrete. While I'm sitting there thinking "I can't believe those F###ers did that", the narrator is chortling with glee, something like "that'll teach him to respect the law".