I always tell dealers to leave their advertising off my car unless they want to pay me a royalty for being a rolling billboard. Most comply, the others I point it out during the pre-purchase inspection & tell them it needs to come off to my satisfaction before I will pay for the car.
The dealer i buy most of my cars asked before they put it on. I always tell them if you think your dealer give a good service then put it on, when i get a bad service multiple time i just take them off.
Not a chance. This is ones of the first things I bring up when we're close to closing the deal. I told my sales guy & the sales manager that if it shows up on the car I'm walking away from the deal... I reminded them both during the entire waiting process (no stickers, no cleaning, etc) JUST in case they had a short memory.
I've seen paint scratches from a dealer putting stickers on and failing to cleanly get them off.