I personally know of several, including one who had his credit card cloned, which he used once in one store. Another who was in a taxi that was stopped by another taxi and his driver threatened with a machete for picking my friend up 'at the wrong place'. Another who got very tired of taxi drivers in Bangkok refusing to use their meter. Another friend, in a wheelchair, said he would never return, for the very obvious reason that he found, on his world travels, Bangkok to be the most difficult city he had found anywhere for people such as him. Another friend came and had no problems, but it was been there, done that, and nothing great to return to.