I adhere to the opposite approach. When I propose straight boys who have no other contact to Farang (assumption based on the fact that I hunt away from tourist areas and they don't speak English), I offer 500 for wanking. The logic is the following: a boy who is curious about gay sex, or just doesn't care, will gladly accept as that's a good offer by their standards (300 THB minimum wage). But one who is either disgusted at the thought of gay sex (and won't be much use in bed) and is greedy will ask for 1000 or more. No thanks.
Details here: Dating Thai boys (61) Recruiting straight boys for gay activities
https://christianpfc.blogspot.tw/201...-straight.html
A Farang friend who had orgies with groups of boys in his room in Bangkok paid 500 for those who just join naked, and 700 for those who fuck him, and they were coming in droves and brought friends. However all very average by my standards.