You can't even trust the big taxi brands anymore -- the last time I was ripped off it was by Jinjiang (I documented it either in this thread or a related one).

With GPS being prevalent, the most common scam I've run into is doctoring the meter, but by 5-10% distance-wise. So my standard operating procedure upon entering a taxi is saying my destination, and the precise distance. That worked until the last time. It does cause a lot of grief, but I enjoyed lecturing the guy the last 1/3 of my ride on how he shouldn't rip people off and how he's lucky I'm not calling the police.

If the driver is not wise onto me knowing their scam, I let them drive into my compound, and I tell them I've alerted security not to let him out. Then we start the lecture / negotiations. I'm of the idea not to pay them anything at all, but my wife thinks I should pay them something. She's too soft.