While in Ao Nang in October 2012, I used motorcycle tuk-tuk number 075. It is painted on the back at the top. The driver spoke some English and agreed on 60 baht for my fare outside of town. In the middle of the day, broad daylight, he pulled over and demanded "give me 200 baht or you walk". I calmly tried to negotiate with him (I'm local here 3 years) and he immediately attacked me for not paying. He stopped and fled with the tuk-tuk when some locals happened by and were ready to help. Police report did nothing. All they offered to do was find him and bring him to the station so I "could talk to him". No assault or attempted robbery charges, no follow up, etc. I had the number of the tuk-tuk and his sunglasses with finger prints all over them. They magically disappeared at the police station. This type of thing is not uncommon in Thailand so avoid riding alone and take a photo of any vehicle you get into. Keep in mind that these are all controlled by local mobsters and the scenario is a no-win for you. If you pay him, he continues to scam people. If you fight him and win, HE will report YOU to the police and YOU will go to jail. Ironic, huh? In my case, no investigation or jail time for him. Luckily, he got nothing and I escaped with minor bruises, some cuts and a few sprained muscles.
If you rent a car (as we did), remember that there are most deaths per capita in Thailand. So if you are not used to right-hand wheel, don't like to drive in dark and like to follow unfamiliar scenes, take a taxi or driver! A couple of times I had to give way and turn to bank of road and if you get in the middle of accident you probably are wrong, as turist mostly are.
It's a adventure, but be carefull.
If you are travelling without quides be aware that the maps are not good (we had only some advertisement map) and there a not alvays the distances in signs. We where looking the Tom Pariwat waterfall and as you can see no kilometers. We sow some four signs followed the right route for 30-40 kilometers, and finally we turned back cause night was coming.