"Hello, I take you anywhere, many temple, jus' twenny baht!" So begins one of the oldest scams in Bangkok's voluminous book; I still fell for it. What the driver really wants is a petrol token, which will be given to him by someone at the tailors' or jewellers' shop he will inevitably bring you to after a short tour of the neighbourhood's least spectacular wats.
Outside most of Bangkok's main attractions.
Updates
This happened to us, but we also heard it can happen generally if you get a tuk-tuk. It's not a reason to not get one, because they're a great experience. If it does happen the telephone number for the thai tourist police is always posted on the inside of a tuk-tuk, together with the drivers ID. Ring them immediately and do not get back in!
Is this your business?