Nowadays many breath tests are organised by Pattaya police at main crossings, such as Pattayatai/Second Road and Pattayatai/Third
Road, and by Banglamung police at the railway crossings, also the one halfway between Soi Khao Noi and Soi Khao Talo. (The latter one is where you get when, coming from Pattayatai, you cross Sukhumvit Road and continue straight on.)
In Thailand the legal alcohol limit is 50mg per 100 ml of blood (units shortened to 50mg for convenience), and 0mg for professional drivers (this compares with 80mg in England and 50mg in Scotland + most of Europe) .
Thai police use two types of breathalysers:
portable yellow sticks with a funnel-shaped end (you have to breathe in) and two lamps on it (a red lamp apparently meaning "in operation" and a lamp that lights up amber when you are "safe");
devices with a ticket printer for those who fail the test with the portable yellow stick.
Unlike Thailand, Belgium and Germany have modern electronic breathalysers with a display and with hygienically sealed disposable single-use mouthpieces are used; I have no experience with breathalysers in the other European countries where I have been
I have been checked twice up to now without problems, but I still distrust those Thai breathalysers and, if I can, I will avoid those checkpoints. (Remember the fake explosives detectors used in South Thailand.)
A bar girl I know for many years was less lucky and got a ticket mentioning "140" (140 mg I presume).
She was told the limit was "050" (50mg I presume), with a tolerance until "060" (60mg I presume).
Instead of awaiting her day in court and be fined 10,000 baht, she told me she managed to pay 5,000 baht under the table.
I guess the tariff will be higher for farangs. TiTs (This is Thailand, stupid).