I agree with you always make sure the food is prepared and going to busier food stalls. I have not travelled to South East Asia but in lived in India and street food poisoning sometimes is a real danger. I heard some stories about people who have eaten very spicy food and then discovering that it was not fresh and they had to go to the hospital. Fortunately I ve never been to the hospital but sometimes I had some problem with stomach in particular during the summer and the monsoon season.