there are alot of cops out there that are real good ppl and are easy to get along with, but the few that are a*s holes spoil it for the rest of them.in my previous car (not a 'line) i had permits for absolutly EVERYTHING, and i still managed to get a yellow for something that was on the permit, his excuse was that in his opinion it was illegal and therefore i would have to get it inspected, and i was being very civil to this cop, so trust me permits are a great help most of the time, but if for some reason the cop really wants to sticker you, they will, permit or no permit, but as most of you have said, it comes down to attitude, most of the time, be just dont be a d*ck head towards them and they are USUALLY ok, not all the time.
my 2c worth