It isn't any foreigner or any Thai - one example or even many hundreds cannot be generalised to everybody.
When I read the title, I thought maybe this is from Bob, looking to denigrate all Thais and to infer all associated foreigners are gullible enough to fall for the ungrateful Thais.
Also, I have noticed there isn't any "middle ground" with you - Nightmare or Paradise
I have been in Thailand for more than 20 years and in a few different places and, while reading and hearing about some peoples experiences, I certainly do not deny there are those who take advantage and those who let them!
Where I have lived for 7 years now, my life is 95% around Thai people and am satisfied that most of them are not of the characters you write about in your post!