Is there more unburned fuel in a 1/2 a engine than the larger sizes?[/QUOTE]
LOL Yes, 1/2 A's are a slimy mess after running. High oil and usually with no directed exhaust. Also, in order to start you squirt raw fuel in exhaust port which allows raw fuel to get on everything as well as any unburned fuel. Many are hand launched which requires them to be wiped down after each flight because you cannot hold them. These are just some of the reasons some hate 1/2 A, but I love 'em. As for the dope, my experience is after a short while, when you wipe the plane clean, what ever color it is starts to come off on the towel.
John