It's real simple, you will almost never meet a Mexican cop who speaks enough English to matter so smiling and not arguing really does help. And it is important to remember in any country you wander, whether you speak the local languages or not, never let on that you understand the words of the man holding a gun. This provides an edge by making it more difficult for the cop/soldier to get you to comply. Never, I repeat never, smart off or show signs of hostility. Acknowledging that whoever is detaining you is in complete control is a great, and sometimes sufficient satisfaction for them. Deal with their machismo without cowering though. Although having rode every corner of Mexico for over ten years, and am always speeding, I still have not encountered the negative situations described by so many others. Keep a positive attitude and you'll have less problems wherever you travel. If you listen to all the babbling crime reports by chat-room "wise men" and stories of crooked cops, you will surely have bad experiences. Keep your eyes on the road and not on the ditch. That being said, I discovered that Central America and Africa was far worse for shakedowns. Try this whenever stopped-- Keep smiling and whether guilty or not, recognize the futility of arguing and request to pay the fine...by fumbling through your dummy wallet and eagerly handing the cop a travelers check. He will surely decline that offer, which you follow with insisting that he accept your credit card. Of course he'll ask for cash for which you only have a tiny amount of in your dummy wallet to placate any other roadside robbers. Because most often, the only reason for being stopped was a shakedown, the cop will quickly realize that he is wasting precious time better used on drivers of big, expensive SUVs.