Memoir? Or not?

I'm curious about something, and if it's already been covered on the site at some point I'll apologize ahead of time, and maybe someone could direct me to any pertinent threads.

I had a very strange reading experience recently with a Southern Gothic "memoir" entitled Sins of the 7th Sister. It was a rip-roaring read but in the end I had serious doubts about its overall veracity. Truth is stranger than fiction - however - SO many of the incidents were so over the top that I began to feel that it was actually a "based-on" rather than a genuine memoir.

i.e. - and I realize this is a very serious thing to say - as if it may have been 80% novel which was marketed as a true memoir. Which it was. Nowhere in or on the book does it say "novel", or "based on". It does sport the words "true" and "memoir" on the cover.

I guess my question is, are memoirs sometimes crossing the line past the normal name-changing etc. into much more fictional territory?

(notwithstanding the blatant, which get caught out as with James Frey - I'm thinking more of instances where the reader would never really know definitively one way or the other)

Right, it's the possible bamboozlement factor that worries me.

Specific to the book I cited, the author has dropped off the map. In fairness, that could be due to the content of the book, if it is in fact all true. There's some very gasket-blowing stuff in that story if it really happened. I know he changed all names and locales, because none of that is supported in searches. I did ask a friend of mine (whose family goes way back in the general geographical location of the book) and he recalls no people or incidents which fit. And believe me, locals would have remembered this family!

I don't like having doubts about a nonfiction work, not one bit. But this one sure has left me wondering, and a tad less trusting in the word "memoir" on the cover.