This article says a lot, and even suggests it, but ultimately, the reason editors don't work too hard at spotting fake memoirs is ...

They don't have to worry about veracity! The reading public is too stupid, and too willing to accept the "artistic license" or "it's emotionally accurate if not factually accurate" rationales, for it to be worth their time or effort.

Face it, people will still buy these books anyway. In fact, I'm betting that sales of Frey's book actually went UP after the "fiction" revelations. "Scandals" like this definitely bring attention to works that don't necessarily deserve any, and might increase sales.

As long as editors can fall back on rationales such as the aforementioned, they have a ready excuse for being duped and for passing along fraudulent* books. I wonder if there are editors who might purposely NOT investigate "memoirs" they're publishing, knowing that should they turn out to be fictitious, they might actually sell better.

* Yes, calling fiction a "memoir" IS fraud. No one put a gun to these authors' heads and forced them to assert veracity. They could just as easily have written and sold these books without any claim to authenticity.