Time to share my 'tipping' tale. My wife and I visited the US for a holiday back near the beginning of the millenium. One of the traditional highlights of a US holiday is Las Vegas - where traditionally the slot machines subsidise the food courts and all sorts of other entertainments. Unfortunately, this trend was being hit hard by some financial downturns and so we had to pay for our meals.
We stayed in one of the large hotels on 'The Strip' - and when I say large there is a monorail that runs between many of these. It's a long hike! (And of course you cannot get to your hotel room without crossing the 'gambling floor'.)
So, back to the tipping story. We had been to the Las Vegas Hilton, which had an amazing interactive ride called The Star Trek Experience. Ride was great, wife got her photo taken with a Borg prior to assimilation, then we jumped into a taxi to go back to our hotel.
I didn't really focus too much on where the driver was going, until he pulled up to the hotel next door to (and 500 metres away from) to ours. I told him it was the wrong hotel, and he drove us to the correct hotel.
Mrs P got out of the car while I settled the bill. I counted out and gave the driver exactly what was on the meter, and exited the vehicle. A few seconds later, he yelled out of the window "Hey, what about a tip?"
My answer, as several people gathered to see what was going on, was simple: "Your tip is to take passengers to the correct hotel next time!"
It may have simply been the warm air, but I felt a mini-cheer of approval from the onlookers - many of whom had no doubt been scammed in this or another manner in the past.
So even in the US, if the service is below standard (and in this case increased the base cost significantly), I will not pay a gratuity that is supposedly based upon good service.