I'm guilty of doing it once
Picked some big mouthed numskull from the station, he wanted to go to a nearby town (about 20min away maximum).
I was 10mins late and apologised for being late as i always do (but i'll only apologise once and thats it) he was booked for 8am and i arrived at 8.10 he said he had a meeting in the town at 9, and if he wasn't there on time he'd "have my job". so (trying to keep cool and not throw him out) i assured him he'd be there on time and set off.
He kept going on about me being late even though he'd booked the car an hour before, so i took him the very long way around and a £15 fare turned into £25.
By the time we got there with 10mins to spare he'd calmed down and gave me a £5 tip!
Trouble is, he asked me to pick him back up again 2 hrs later but i coudnt remember which of the long routes i'd taken him!! to get the fare back up to the £25!!
That'll teach me!!