Spinal Tap was funny because if you knew a little about heavy metal, you saw in-jokes all over the place. If you know anything about porn, this mock documentary will leave you cold. Everything in it rings false.

Spinal Tap was funny because it took a familiar world and pushed it over the top. This film is decidedly not funny because it paints a picture of how porn is made that bears no relationship to the real world.

The acting here is uniformly awful, but that would not matter much if the core idea of the movie were good. But it's not.

Is the sentiment of this review positive or negative?

[a]. negative.
[b]. positive.
[a].