You occasionaly see Thai boys wearing speedos on Dongtan Beach, usually in the later afternoon when they are looking for customers. A few years ago you used to see a lot more, but I think Gayromeo has caused the decline. Over the years I have taken quite a few boys to the beach and also to Samsuk Sauna and have suggested to them that I would like them in speedos, preferably brief and with a pouch at the front. I suppose thats me trying to get the other older farangs jealous and it helps me to get horny.
Generally they are reluctant the wear the ones I have selected from the shop in Tukcom or from the one in the Jomtien Complex. Having got them on, they usually use a towel to cover up. It is part of Thai culture which is engrained in them and you have to accept this. I have no problems in getting them to wear them in my room.