Okay, I'll go first...

While I enjoy reading another person's bumper sticker, I won't put one on my own vehicle. Stickers create a cluttered appearance, degrade over time, become obsolete (in relevance), and are a job to remove.

I've not been able to place any stickers on my own bikes. I even fancied one of Retrogression.com's stickers that say "Ride" with the image of the late Sheldon Brown. Who wouldn't want Sheldon's image on their bike? I can't pull the trigger...

So, my vote is "no". I'm a hopelessly rigid old fart, though, if that matters any.