Thailand is a relaxed country to visit but that doesn’t mean that anything goes. Unfortunately, some tourists forget that when they hit the beach. Although Thai people in tourist resorts are generally very tolerant, partly out of practicality because tourism brings revenue and jobs, there are some things that show disrespect to local culture and customs and should be avoided.
Topless sunbathing by women is frowned upon by local Thai people. This is true for everywhere in Thailand, but in particular on some of the southern islands and beaches where there is a local Muslim population. The fact that it’s highly unlikely that any Thai person will actually reprimand a foreign woman for sunbathing topless doesn’t make it right or acceptable.
I’ve spent the last week in Phuket including a stay on Kamala Beach and I was surprised at the number of topless foreign women who were walking along the beach. They were clearly ignorant of local customs which is made worse in Kamala because there is a large Islamic cemetery just behind the beach.
It might be a cheap and cheerful beach-side restaurant, but if men don’t have the courtesy to put a shirt on it shows disrespect to the owners and other people eating there and it doesn’t go unnoticed by Thai people. In Thailand, food and food etiquette is important and no man should need a sign in English to tell them they need to put on a shirt before eating at a restaurant, even a beach-side restaurant.