Just being in the presence of police officers, at least the police officers I’m ever around, is an unpleasant experience. The sheer fact that you’re in the same vicinity as they are, and that if they so chose could harass you to ridiculous lengths on nothing more than a whim, is just uncomfortable and unsettling. It reminds of the feeling I would get as a little kid being around older kids with whom I wasn’t familiar or were aggressive, which I think is a pretty relate-able feeling. As a kid in those situations I felt overly scrutinized and objectified, I would try to say the right things and act the right way that would garner approval or appease the assholes and lighten things up. Pretty quickly I realized it didn’t matter what I did or said, the fact that they were in one sense or another superior to me and held power over me is what made them assholes. I would by treated based on their split second impulses, not based on their reaction to my behavior
I by and large feel the same way about police officers. If they feel like fucking with me or my acquaintances they will do so regardless of our behavior, simply because they can or because they feel like it. And it’s even worse because for the most part those ‘mean older kids’ really weren’t capable of doing much besides taunts and shoves, things easily shrugged off. Police are capable of at the very least wasting plenty of your time, and at worst ruining your life.
TL;DR Cops are inescapable, unpredictable dicks with the tools to actually fuck with people in a serious way.