When I'm on my bike, there's a 99 % chance I'm in a wool shirt. Even if you can't see it under other layers. I wear wool against my skin because it's comfortable. When I'm not on the bike, there's an 80 to 90 % chance I'm still wearing a merino tee. Same reasons. Most of mine are a solid color, or two colors, and a few have logos or designs, but nothing too obnoxious.

I don't have bumper stickers on my car, either.