The answer is no...and yes. If a listing agent agrees to a cost credit without demanding to see a good-faith-estimate, they have no recourse. Oftentimes, the credit exceeds the costs and the originator should use the "excess' to benefit to buyer in a lower rate. Sometimes, the loan originator "hoards' that money
Brian is correct. As the listing agent, you need to request the buyers good faith estimate upfront before the offer is signed around and the seller has agreed to pay a certain amount towards closing costs. If you rely on the HUD, you won't know what rate is related to the cost. You can read more about this by clicking the link below.
If you have a good faith estimate though I take it you can go over the figures and see if it is happening, yes? And the settlement papers would show that as well? Or is it lumped into some other figure?