Yeah, OK, but as ggunn says, don't allow it to happen. Know what the rate is. Hail the cab, reach your destination, pay the correct fare, thank your driver, and walk. Those drivers that try to impose the tourist tax can sit there all day yelling, screaming, muttering or whatever - doesn't matter - pay the correct fare and walk. The end.
I can see both sides. Yes, you can take more control of your situation, pay in pesos, and agree on rate beforehand. On the other hand, people go on vacation to relax not be on friggin' guard 24/7. Just because someone CAN take advantage of you doesn't mean the MUST or SHOULD. And if they do then they have to accept the reputation they have earned.