I attended an IDPA match yesterday and saw this bumper sticker on a pick up truck. "Heavily Armed - Easily Pissed".
I would think this sets the owner/driver up for the general population to anticipate and profile that a hot head is in the drivers seat.
Personally, I would be a bit anxious seeing the fellow get out of the truck after reading it. Maybe escalating my situational awareness level up a notch.
I have no bumper stickers of any type on my vehicles so that the general public cannot figure out what I am for or against so to speak.