Love the street food in SEA, but yes as @lam.la01998 and you said it can be tricky sometimes. I had food poisoning in Siem Reap (Cambodia) during my 2nd visit and luckily it was my last night there otherwise the rest of the trip would have been ruined. I flew back to Bangkok the next day and ended up checking into an expensive hospital...thank god for my travel insurance. I thought my stomach could handle anything and everything, how wrong was I. I ate very basic meals upon my 3rd visit to Siem Reap as you can imagine why.
Still need to visit Saigon, but loved the north part of Vietnam - Hanoi and Sapa.