How about asking him how much he earns? How often he fucks his partner...See how how polite and sweet he reacts to intrusive questions.
You have no obligation to be polite to intrusive, rude, insensitive individuals.
If it's face to face as long as you have his money first- you could pretend, you don't hear and divert the conversation to the weather, netflix, what you ate last night, anything mundane, he'll get the messege.
One of my techniques for irritating clients is, I'll say merrily, I need to go bathroom and leave him there for five minutes. Check my phone, do my lippy, tidy the bathroom etc If he repeats, off I trot again. You've seen the Dog Whisperer? That stops his flow and magically improves behavior never had to do it 3 times.
If it's on the phone, I hang up. AS VC says I think it's grooming you for bareback.