Just re-entered BKK for the third time since I got my DTV in November. Handed over my passport, boarding pass, laminated DTV letter and had my TDAC QR code ready on the phone. 
Zero questions just like every other time. Stood in line for 20 minutes, but actual time at the window was 30 seconds.
I suppose any I/O could make it difficult for anybody, but my experiences have been smooth as silk