Well I do things in the correct order.
1 Polite introductions.
2 Attempting to establish if he is a money boy, without asking directly.
3 Asking what he likes doing.
4 Once he has said he likes doing the things I want, I make it clear that getting tipped is contingent on providing certain services from that list.
So I'm merely asking him to do what he promises. Which is still respectful.
Perhaps about 5~20% drop out at step 4, so I can only deduce that they were not willing to do what they initially promised. Exactly the result I'm looking for. It keeps non-performers away, so I never have to follow through on the zero tip threat.
I started doing this around about 2017, after a few Cambodian bar boys made promises that were not kept. I've had far better results since then.
I treat the lads with respect. I expect that to work both ways and both parties should keep promises.
Almost all of them ask for a repeat off & often ask me to come to their bar, even if we met via Grindr.
When they know I'm a butterfly, they sometimes also introduce me to their friends.