Khun Jean

a signed and stamped receipt.
And the chanot of course.

With the amount of soot in the air, no building looks good after a few years. You need to be away from the busy parts of bangkok to find reasonable clean (outside) buildings. The outside of the buildings is approximately the same as the color of your lungs when you live in bangkok long time.
Painting is done when it is build and almost never afterwords, meaning the paint will fall of, the soot sticks to the concrete like glue.
Combine it with some algae, and rust and you get a very colorful building.
The inside depends on the 'class' of people living there and if they pay there monthly bills to maintain the building.
All these things are more obvious with older buildings (10 year or older). When these still look good you at least have a good change the ones that maintain it are doing a decent job. No guarantees for the future but it at least you have some indication, newer buildings always look good and that can be a real problem later as in Thailand it is the norm to do as little maintenance as they can get away with.

What reputation? With no accountability whatsoever, starting a company with a nominee.
I see only failure. Especially when you are that far in your decision making and still have to ask these questions.
Better walk away from this one, educate yourself and find an even better offer later.

All of mine give at least 10% and also appreciated in value the last 5-10 years although that is constantly being cancelled out by inflation.
Older buildings that still are in good shape are more secure then new ones (often lousy build quality), around 25-30m2 seems to be the sweet spot for a good return.
Next month i am going to buy another 4 or 5.

I always use 5% as an easy figure to calculate with.
In practice it is always lower than that, but calculating yourself rich is worse.
Even if it is within 5 year your only of .3%.