I have never mouthed off to a cop, been hostile, or anything. I have no record, have never been arrested, and have never had to deal with the police for anything but traffic violations.
I must send of bad vibes.
I have never been stopped without being given a ticket. Ever.
Partly, although I am in my late 30's, I look in my 20's and scruffy.
I almost always get my car searched crossing the US border too.