Cheating Taxi drivers yes It cost me 1500 php to get from the airport to Ermita. I've since made the same jorney many times and it's usually between 150 and 200, the cheapest I've done it is 110, but that was at 4am in the morning.
The dirt, polution, overcrowdedness and noise didn't really phase me, I've spent a lot of time in India so am used to large 3rd world cities. Whenever I've been in Manila I've always been in the company of a Filipina g/f who acts as a tour guide, interpreter and negotiator, so it's always been pretty easy for me.
On my last trip I decided to go it alone from Imus to the SM mall in Bacoor, getting a jeepney there was pretty easy, but finding the right one back to Imus was more difficult, but I made it, and even if i did get ripped off 12 peso's each way was a bargain
No negative experiences for me, other than the ex g/f Can't wait to get back there in 15 days time