When I see someone from the sticker club I always has to imagine the reaction of client at the first meeting on which he shows up with his laptop.
Professionalism < 0
Ridiculousness > 9000

If you base business off of a simple thing like stickers then maybe it's good for the dev you didn't do business with them... :p

I don't mind. My lid is always full of stickers and I always managed to let my expertise shine, not the stickers

Meh. That's the same as hiring anyone based on appearance instead of aptitude. Those people not hired are lucky because people who run a business that way are more than likely a horrible experience to work with. Hell, I'm clean cut with no stickers and I wouldn't want to work in a place like that. To each his own, though.

I would never hire a developer with a clean brand new notebook cause this makes me really suspicious ...

Are you serious? I've got 20 years of "doing the impossible" as a systems engineer and my laptop is covered with them.