Originally Posted by
SKT-DK
Temperature and year does not make it acceptable to dress like a beach club attendee in every setting

I would hazard a guess that you would not wear shorts outside in the heat of summer in the UAE during Ramadan, despite 40+ degrees?
I do however, agree with you that there is a difference between day-time and evening time.
I would make a distinction between stylish "resort wear" and "beach club" attire, with resort wear being a more formal. Nobody has said swim trunks and flip-flops are acceptable. You are correct, I wouldn't be outside in 40° weather...but we're talking about indoor Bangkok spaces.