...Well, Joseph, i have been to Thailand countless times over the last 35 years, including 2 years when i more or less lived there and i have eaten from street stalls and night markets all over the country and never been sick. The Thai people are very clean and hygenic so i would not hesitate to eat at any stall in any town or city. The ingredients are fresh and cooked right in front of you (or at some stalls the food is in large containers that has been cooked earlier). I cannot recommend a specific stall or street but if you see many local Thais eating there you know it will be good and you cannot go wrong. The link below may be of interest to you, as i have eaten at all those areas. I would also add the foodstalls at Chatuchak weekend Market to the list,...
...I second what davidjo said about street food in Thailand. I ws there only once, for 16 days, but never saw "bad" food either. I examined the stalls before ordering anything & they all met stringent expectations...