A friend of mine beat a speeding ticket once by demonstrating that it was physically impossible for him to have slowed down from the claimed speed and stopped in the location where the officer wrote the ticket.
A guy from my parents' church beat a speeding ticket by demonstrating that the motorcycle cop would have had to reach a speed of over 160 mph in order to clock him at the speed measured at location A and then catch him by location B.
I once failed to beat a speeding ticket by not noticing that the officer had forgot to introduce the ticket into evidence. I introduced it, the judge said "Really? Are you sure?", I missed the hint, and since a ticket is evidence of speeding in Massachusetts, my case was kinda shot...