Prostitution does become legal once corruption hits 75, though, and that clears the bribe from taverns.There is a base income which gets multiplied by reputation somehow. From personal testing I recommend not to use any goldwalkers directly in your taverns, as there is a subtraction for bribes immediately when doing so. Regular goldwalkers/escorts will make more money when not being attached directly to a tavern, since there is no bribing involved.
I have like 3 goldwalkers assigned to 2 taverns, and I have no real clue about how much money they're bringing in.
I'd probably be better off just having them be regular goldwalkers.