I never really understood the sticker argument. Having a sticker(s) doesn't necessarily mean that you think that you are sponsored, as the overwhelming majority of people aren't. It could just be a matter of a person supporting particular companies, looking for a certain "motif" or hiding dents and holes. Honestly, as surfers do we have to nitpick every last thing?
I had a couple stickers on my pickup truck windows. It was more of a way to put up a flag, so to speak, and say whats up to other surfers. At least in OBX, most 4X4s have either surf stickers or fishing stickers. It's a war out there and sometimes you gotta choose sides.