Personally, I've eaten seafood of all kinds all over Thailand, on the beach, at street stands, simple eateries and fine restaurants, and I've never ever been ill from it.
But you'd be advised to stay away from buffets in tourist hotels.
The only two times I have been sick were after eating at tourist restaurants which I went to with friends over my better judgement. (Not seafood.)
I only drink bottled water, but you can bet that the vegetables you eat and the dishes you eat from are not washed in bottled water. Even so, we don't get sick. My Thai friends wipe off the dish and eating utensils with tissue.
Like Bill2p, I eat seafood at restaurants and mom & pop food stalls all over Thailand without ill effects. I feel most Thai food vendors pride themselves on serving good food.
For drinking, I would suggest sticking with bottled water. While the tap water in cities is purified, your system may still not like it.
One other thing to keep in mind, while most folks blame what they ate for giving them Dehli Belly, quite often it is what you touched before eating that did you in. We tend to over look washing our hands before eating when traveling.
-:- Message from TripAdvisor staff -:-
This topic has been closed to new posts due to inactivity. We hope you'll join the conversation by posting to an open topic or starting a new one.
To review the TripAdvisor Forums Posting Guidelines, please follow this link: http://www.tripadvisor.com/pages/forums_posting_guidelines.html
We remove posts that do not follow our posting guidelines, and we reserve the right to remove any post for any reason.