I also believe that is the case. I guess, these venues are frequented by Asians and might have got something to do with drugs/gambling. Some places in Bangkok came recently in the news for similar facts, maybe same owners? I am pretty sure that a normal acting tourist might get a drug test when checked, but when they ask you your passport and say i left it in my room at X place , at a polite manner they will not even check further and just let you go. Btw i did get stopped frequently in Thailand for alcohol test, drivers license , speed limit ( that was just ripoff but ok) and to be honest, i never gotten into trouble , besides paying a fine. Also the police were always friendly and understanding. React normally , calm and cooperative and i am pretty sure not much will happen.