Ok this is my own opinion based off my personal experiences with Warfield Jr as a man and as a medicine man:
I've been to quite a few of his ceremonies and sweats and I feel very strongly that what he is doing is NOT fraud. I believe his intentions are good and that he helps most people who come to pray with him. I agree that praying in a Lakota way when one is not Lakota creates a lot of confusion about what is happening and that is where much of these accusations come from.
Warfield himself does not charge for ceremony. The hosts who invite him charge to offset the cost they have to put out to fly him out to them and for his accommodations. This was not always how it was. The hosts used to put up the costs themselves but one of them (my former mentor, who hosts him to this day in Somerville, NJ) started charging her students to attend so she didn't have to pay a dime out of her own pocket. Other hosts got wind of this and started following suit. So if anyone is guilty for selling ceremony it's my former mentor and the other hosts.
Warfield as a man, however, is best kept at a distance. It's true he is warm, funny, friendly and geniunely desires to help people but he is also manipulative, arrogant and a bully. You do what he wants you to do or f-- off. He has no one to check him and tell him how he is mistreating people, he's surrounded by "yes men" and people who want something from him, so they will not be honest with him. How else do you expect a man to act when he's treated that way?
I know also he does hold sundances each year on the reservation. I have been invited several times but never went. I feel that's crossing a line for me to go, since I am not Lakota, so I can't comment on what happens there from experience, however I have only heard good things about his sundances and his extended family that still lives on the reservation.
I once considered Warfield a beloved friend and in some ways a teacher. I still respect his work and stand by it. It is his treatment of others in his personal life, myself and my sister included, that made me decide my life is better without him in it. I feel it is important for people who do choose to pray with him to know the difference between his work and himself. Too often we hold spiritual figures to an impossible standard of behavior. His actions as a person do not discredit his actions in ceremony. One day he may lose his power, possibly because of his personal behavior, I don't know. But last time I prayed with him this was not the case. Just be warned if you try to be his friend. That's where you run a risk of getting burned.
