Nasdijj - Navajo or Not?

In all the heightened interest with James Frey and "Million Little Pieces," other memoir/biographers are coming under fire for having outright lied about who they are and what life experiences they lived through.

Yet another. This one named "Nasdijj," who claims to be Navajo, but instead has been recently outed as a white man from North Carolina. He completely fabricated stories of having grown up on a reservation, and was also an award-winning author with "The Boy and the Dog Are Sleeping." The book was even optioned for a movie until the producers backed out because he was becoming difficult when fact-checking time rolled around.



Here are links to some of the articles and controversy surrounding him:
Doubts raised about Indian memoirist
White Man Writes Navajo Memoirs
Nasdijj Interview (old)

And his own blog, which I found rather obtuse and disturbing:
http://www.nasdijj.typepad.com/

Where's the line? When someone is writing a "memoir," how much of it should be true? Some of it? What percentage? Apparently Nasdijj completely fabricated his. Why is it that the memoir genre continues to sell in gangbusters (although I suspect the bottom has now fallen out of this genre for awhile).