It is just far too easy to make a bribe with consulting services. There is no good way to measure the real value of consulting services, and their cost can be massive. If a crooked CEO gives his accountant bags of cash to cook the books, he may be caught and both the CEO and the accountant can be sent off to jail. If a smarter crooked CEO instead hires his accountant's accounting company to a 100 million dollar consulting contract, in exchange for cooking the books, good luck proving a bribe took place. The accounting firm will surely put in a hundred of consultants on the contract and they will surely produce long reports with stacks of technobabble and graphs. Who is to say how much that is worth.