Do you ever slow down before you see the police? This happened to me. I was going about 10 kph above the speed limit. I kind of thought that I should slow down. After I slowed down I saw someone getting a speeding ticket.
Nah, but my aunt's bf is like this though. He'll be going like a million miles an hour, slow down when a cop is in view, and go right back up in speed once said cop is out of sight.
My copsense is impressive. But many people do what you're talking about. They are exactly the individuals the police are looking for.