As far as I am concerned, “r” orginal sound in Thai Bangkok accent, can probably be included in the accent, which is similar to “received pronunciation accent” in British English. The Royal Family, well-educated people in the upper status,the scholars,the Thai news and some of the artists performing in the social media, speak with this accent.
The “r” sound, which is pronounced “l”sound in Thai, is most often heard in Bangkok at the present. This is the way people trying to ease their pronunciation because the "r”sound uses more muscle effort than the "l”sound. Some people even criticized it as "lazy language", and actually you can hear this all over Thailand according to the influences from other Thai dialects as well.
Anyway, as I am a linguist, it is concerned as one of Thai Bangkok accents.
