I posted a while ago on passing two laser camera cop vans while speeding. Both times I was in the slow lane when I noticed them and from the position of the lens and type of gun I'm sure it was pointed at the fast lane.

My rule of thumb - never speed when you feel the urge to put your foot down - that's when most people will speed and the cops know where those places are. Use your head and you'll avoid them. Not had a ticket since I was 17 and I do like to drive fast quite often (safely of course....)