Actually, it's questionable that she was successful with the NPC groups she supposedly "infiltrated."
Several of the conversations she records she could only have gotten if 1) the girls she was following were wearing wires or 2) she made it all up. The level of detail just doesn't wash.
Plus, she has never been "outed" which I find hard to believe - unless she's had full plastic surgery. I can't imagine how this woman could be hanging around a school all this time and no one has said since the book's publishing "hey, isn't that..."
I personally believe that the girls she shadowed are completely fictional and that she created their stories from emails she received while "researching."
Oh, and I highly doubt anyone could do anything like this in an NPHC group - they can't even do it on GC.
