What is the test for determining whether a bribe can be obtained through the medium of a go-between or intermediary?

The trial court relied on People v. Davis, supra, which holds "when the bribe is accomplished through the medium of an agent, or go-between, or intermediary, the mere fact that the evidence is conclusive that such emissary is the agent or accomplice of one of the parties does not necessarily determine that such emissary is not likewise the agent or accomplice of the other party to the transaction. We can see no impossibility, legal or otherwise, in a person acting as the agent or accomplice of both the bribe giver and the bribe receiver. Each case, of course, must turn on its own facts and circumstances, and if there is any doubt as to the proper status of the emissary, the question is one, under proper instructions, for the jury. [Citation.]" (People v. Davis, supra, 210 Cal. at pp. 557-558.)