What is the spiritist thought concerning mediums that are on TV?

I think it is fair to say that those people most knowledgeable of Spiritism would say that the Mediums that are on TV may not always be as truthful as they could possibly be because of the pressures that they bear due to the need to preform, to entertain and to generate a profit.

I’ve read something to the effect that Mediums that offer their services for free and without fanfare can generally be trusted more that a Medium that derives either income or celebrity by their work.