Dr. Carl Trueman makes the case that one can vehemently trumpet confessionalism and still be a cultic, money-hungry, devourer of the sheep.
So just because somebody preaches the gospel, uses the name of Jesus every other sentence and cries when they talk about the lost does not guarantee that they are not a cult leader or simply in it for what they can get out of it.
The key is the culture. One must ask cultural questions of such men, not simply doctrinal ones. Is the culture of their church or organisation transparent? Are there clear lines of accountability which flow both ways, from the leadership to the grassroots and from the grassroots to the leadership? Is opposition to leadership decisions addressed in an open fashion or via thuggish backroom manoeuvres and public derision and isolation of critics? And one interesting question which I remember a pastor once asking in a pulpit when I was college student: how far above the average economic level of the congregation or funding constituency does the leadership live? That little old lady putting her ten dollars in the plate each Sunday or sending in her pledge -- is she funding a lifestyle for functionally unaccountable leaders which is lavish beyond words and built on gospel rhetoric, on not-for-profit tax breaks and on an overwheening sense of entitlement? That can be quite an interesting gauge of whether the church or ministry takes seriously its role as steward of the money it receives. It is, after all, easy to prostitute yourself to the prosperity gospel when your own prophecies of material wealth are effectively underwritten by the desperate dreams of the poor and destitute which you yourself have helped to create and upon which you prey with a depraved and insatiable hunger.
Cultists and con-men are identifiable only by their culture, not by their confessions.
This is another reason for the desperate need for more confessionally Reformed churches. Why so? Because the best thing to do if you find yourself in the clutches of such a pastor is to leave.