Good questions. About 10 years ago it was a combination of signs and word of mouth, now you can add face ache to the mix - Mrs Toot is quite a fan of the social media site for business purposes - hates it for the friends angle and rarely uses it outside business. The places are rarely empty for longer than two weeks which i think is a factor of market pricing and as you say she seems to have got it right - not millions but stable useful income turning to profit in a fairly short timeframe.
Repairs, yes she has local contacts for minor stuff like painting, plumbing and electrics etc. The places are in 3 different locations 2 outskirts of Bangkok, 1 in the Saraburi area and 1 in the Pak Chong area so it's not practical to have one POC.