Apart from Plaa Rah, that is....
1) For me it is coconut milk. I find it sickening sweet and nauseous.
2) I don`t like peanuts in my Tam Thai papaya salat and I don`t like cashew nut in cashew nut dishes...
3) Sugar. The extensive use of sugar or sugar cane extracts in dishes really puts me off too.
Phat Phak Plioaw Waan, sweet and sour veggies.
This dish is not sweet and sour, it is sweet to the extent that I would rather have a lollipop or two.
I dislike salty food as well, but I never found that was a problem in Thailand only in my country of origin.