Actually, I think there is a way to find out by asking them to fill up a TP3 form. There have been others that are telling me that this can be used. I think based on their YTD tax payments I will be able to know. I will ask them to fill this up.

whatever you said you've implied what you're trying to do.
you're the worst kind of recruiter anyone may find out there.

Biggest red flag: judging a candidate based on their salary history.

I pray one day you end up working for a company that will not pay you based on your abilities.

Good luck if you think that way. When you submit your TP3 with fake info, your new employer will use that data to submit your income tax and also your BE form. Later when you do tax filing with different amount you have fun lah to go explain to IRB on the discrepancy.