My unhappy transport experience was in BKK more than a decade ago(before I know how to use Google Map on my phone
).
Used the airport taxi in official way(buy and got ticket etc) going to our hotel near Siam Paragon. Got onto taxi and as soon as the driver left the terminal, he covered the meter and told me a fixed amount for the trip(I think it was 700-800 baht at the time the usual fare on meter would have been closer to 300 baht). I declined and insisted on using the meter twice. The driver gave in and uncovered the meter and continued.
Then I came to realise the driver had used a convoluted route. Not that I know the way to the hotel, but I knew that from the airport we are coming into the city centre from the east. I saw the high rise buildings of the CBD on the right side of me on the freeway(instead of in front of me if we were using the correct route). So I asked the taxi driver are we on the right route, but the taxi driver speaks little English and just kept saying "it's OK, it's OK". Soon after I found ourselves on the south east side of the high rise buildings and finally we sort of did a quarter of a circle on the freeway(from east to south) and entered the high rise buildings area from the south.
As we move into the high rise buildings(now in front of us), there was a big traffic jam(it was like midday, not peak hour traffic) and the taxi travelled at a snail's pace, and with the meter still running on "waiting time" without moving much physical distance. Finally closer to our hotel(where I recognised where I was at that time), the driver said there was little chance of traffic moving and that it would take a long time to get to hotel on road but the meter will keep running, and asked if we would like to get off now with our luggage and walk to the hotel instead(we were about 500m away at that spot)(so his English was not as bad as I thought
). I took that up because the meter was running quickly with the traffic jam and we didn't have much luggage. This ended up at about 500 baht(but not even arrive at the hotel) instead of the usual 300 baht or slightly less.
I think the driver wanted to avoid the scenario where I arrived at the hotel and complained to concierge about the route the taxi driver took. But I wanted to avoid a hefty waiting time bill in the traffic jam to get to hotel(and then the hotel concierge and the taxi driver might agree on something in their language and told me everything was right), so I just bit the bullet and paid the fare.