The Most Telling Thing...
When they talk about how Mapplethorpe hooked up with some older rich gay guy. Basically, Robert became the guy's boy toy in exchange for money (a.k.a. a whore) and the guy became Robert's Sugar-Daddy.
Someone in the documentary says how if this rich dude hadn't bought Robert's way into the art world, then no one would have ever heard of Mapplethorpe.
That pretty much sums it up.
It's the story of the Emperor's New Clothes.
If you have enough money to buy your way into the right galleries and wrap it up in expensive mats & frames, then you can convince the ridiculous art speculators who make up the "art world" that a bunch of gay porn photos are "art" that's worth millions of dollars.
Congratulations to Robert Mapplethorpe for capitalizing on the utter ignorance & lemming mentality of humanity.
I'd do the same with my artwork, but my ethics preclude me from trying to fraud people into thinking something that isn't all that special (or is just porn) is actually "art" with ridiculous monetary value.