The only example was from a bar in Soi Twilight about 10 years ago. I won't name the bar, but it's a brand name that still exists.
Anyway, he was about 2 months away from the desired age. Most annoying, as I thought all the Soi Twilight bars would be respectable in such respects & I had paid the off fee. Far too Fresh for my liking. I sent him away.
The oldest example where I actually checked a passport turned out to be 31 . I think his app profile claimed he was 24 and he was actually worried I was going to kick him out for being too old. No chance of that, when he looks about 20.
Referring back to the thread title, both these were Vietnamese, which is unusual. I've had a grand total of 4 Vietnamese make it to my hotel and just 2 made it into my room.
The 2 successes were the 31 year old and another 20+ lad in Singapore, in about 2008.
The 2 failures were on ID card related offences. The one already mentioned & another lad in Mae Sot.
I suspect the Mae Sot lad was Vietnamese, as he was translating into Vietnamese on his phone app.
I asked for his ID card and he had forgot to bring it. He was of an age where I needed to check ID, so I sent him away. I'd reminded him twice during our conversation, so no excuses. He was also slightly overweight and scowling, so the lack of ID was perhaps lucky for me.
At the time, I wondered why he was in Mae Sot. However, some of my Lao friends have occasionally gone to that border for visa runs, so perhaps he needed one too.