I can answer this question, as a pal of mine was an old, bald fat Canadian that encountered exactly this.
He used to frequent Spotlite agog in Chiang mai.
One night the OZ cricket team were in town, and the girls all ignored him for the fit young sportsmen.
The next night he went back and the ladies were all over him ignoring the sportsmen.
So he asked them what happened ..........
"the guys did us all night, passed us around, talked down to us, and didn't even pay us well"
"You are polite, buy us food and drinks, give us good money and we can sleep most of the night"
These girls are working and not after romance or pleasure, they want the most money for the least effort.