first answer: my foot was resting on the rudder pedals when I took the screenshot.
second answer: the exhaust stains on 109s vary, but in general were fairly light. The 109s were the elite, and kept well-maintained and cleaned. The aces of the 109s were even more elite. I have a photo of Marseille on the side of this very plane and the exhaust stains are faint, light. It's just a sign that they cleaned the plain regularly, I guess.