I don't think you have a strong grasp on bungs at all. Generally it's where some dodgy agent gets some dodgy manager to sign some shit player with a nice big agent fee (or where the selling club agree to get the agent a percentage of any sale value over a certain amount), of which he backhands a chunk of it to the manager for getting the deal done. It's less to do with tax dodging and everything to do with the agent and manager colluding to rob the football club of a big chunk of cash by signing this dross player for over the odds, a practice that is even more crooked when the agent and manager are relatedThe purchase is usually wanted, the buyer funds the purchase totally which includes tax on this purchase together with the cash incentive which is tax free to both parties.
The loser is the Inland Revenue on the undeclared amount.
The buyer frankly decides on the valuation and will only buy if he considers the valuation will contribute to profit. He knows about the split and takes it into consideration otherwise where will it come from ?