Wasn't going to post this. I'm in the middle on all of this. On one hand, I'm certain that there are some bad cops out there, just like there are bad people in any group. And I've run into a few that aren't bad or immoral, but are kinda miserable for whatever reason. But most of them, like most people, are just out there doing there job, and part of that is looking for the nuts and drunks.
A scenario similar to this has happened to me more than once:
I'm driving on the NYS Thruway in a rental Charger. Friendly NYS trooper pulls me over in his Charger. He doesn't ask what I'm doing, just for the license, registration, etc. I volunteer the conversation. "Yeah, these things are pretty quick, and I wasn't paying attention." Which led to "yeah, I clocked you at 85 (this is in a 65). Is this an 8?" "No, this is the 6! It's still fast. Rented it to take a test in Buffalo." We chit chat a bit, he says "Yeah, these rentals never have accurate speedometers. I'm writing you a ticket for a faulty speedometer. No points, but make sure to pay it...and drive safe on the way back".
Does being pleasant always work? Nope... Different guy, different place, deserted street in the middle of nowhere, clear in all directions, I turn left at a stop without the stop. Try the pleasant conversation thing, "Sorry, I wasn't paying attention" which was answered with "you didn't even slow down." Ok, I know when it's time to shut up. I just nodded and took the ticket.
Life is nuance and finesse, or at least a pleasant one is. I don't have too many hard and fast rules.