I will not tip drivers who pretend to have no change and kind of assume that the tip is theirs by right. I will never tip drivers who think they can manouevre a car round tight corners with only one hand on the wheel. Nor the ones who drive too fast and too close to other vehicles - they usually get rewarded by a question-and-answer session on stopping distances.
The ones who only wear their seatbelt when going onto the highway are also not getting a tip. Just like their colleagues who use their mobile phone without a hands-free.
Tough old sod I am.
But I made one guy's day recently when I told him to keep the change from a Dhs 20 note for a Dhs 14 fare.
'?!', he says.
'You're a very good driver - you earned it'.