How do we choose who to listen to and allow to influence us? If they sign a Doctrinal Basis? That may have a role, if they are thoroughly honest, but perhaps looking at the fruit, the well assessed outcomes of their service and ministry is wiser, but takes time to see.
Jesus said, “Beware of the false prophets who come to you in sheep’s clothing but inwardly are ravenous wolves” (Mt. 7:15). They look like the sheep category and behave like the wolf category. Their accurate or orthodox words ARE the sheep’s clothing.