Delhi came to my mind too when I read about KL taxi drivers being the worst. I haven't been to Bombay in more than 20 years. Back then, my impression was Bombay taxi drivers were better than Delhi taxi drivers.
I have heard bad things about cab drivers in Prague, Budapest Bucharest and Sophia too, but I have never had a problem except once when I did not notice that the per/km rate of the taxi was very high. Since it was posted on the outside, it can;t be blamed on the cabbie.

To get back to the topic, KL cab drivers have become worse over the last 6 years. On my first trip, I had only one bad cab driver, who wanted me to pay 15 RM for a 600 m ride. I knew the hotel was not far from where I hailed thew cab. I chose to walk instead. On my subsequent trips I had more and more cab drivers who wanted to charge and arbitrary fare claiming the metre was broken or did not want to go to certain destinations. In one case, I found a cab, after several drivers not wanting to use the metre, only to find out the metre was running really fast. It had already got to 30 RM half way through the trip from Pteronas Towers to the Planetarium. I had done that leg before for about 7 RM. The mtre was running really fast. At first he tried to make excuses, saying that he went way around as the city traffic would slow us down. Going round the periphery, instead straight through, would increase the fare by a factor of about (pi/2), not by a factor of 5 or six. When I inissted that something was not right, he said, "the metre could be bad," and started to negotiate an amount. I told him, I would pay no more than 10 RM and gave him a choice of either accepting that fare or drive the cab to the police station. He became very aggressive and rude. He stopped the taxi right there and told us to get out. I thought it was better to get out than have him drive the cab to someplace where I would not be safe. I flagged down a police car passing by and complained to them. The police drive us in their car to the tourist police, which BTW was near Petronas Towers. I got to file the complaint, but was back to square one. We took another taxi to the Planetarium. It cost us about 8 RM.

In Bangkok also cabbies try to quote fare for early morning rides to the airport. Usually insisting that they use the metre, works. Mere insistence does not work in Delhi.