Or a tint violation if they're bored small town cops with literally nothing better to do.

I used to have a mid 90s bone stock base model camaro that a previous owner had put some moderately dark tint on the side and rear windows. That jackass cop looked so excited to be able to use his fancy toy to test my windows. I had to take a vacation day to try to remove it myself, fail, then pay a tint shop around $100 to chip it off which completely destroyed my rear defroster. Thanks, Officer Fuckup. The best part is in PA the tint regulations are on a tiny addendum that you have to look up because it's not even in the vehicle code (this may have changed since). I'm still mad about it and I haven't had the car for probably 12 years.