I am a 3D illustrator and sometimes use 'base' models that are ready-rigged, etc for my palaeolithic people. I change their shapes, faces, etc to be, eg Neanderthals or Homo Erectus. I have also created my own from scratch. It's a lot of work.
More and more the base models you can buy are coming with full genitalia. I am under no illusion that many customers/artists of these products produce animated films and stills that are pornographic. Even for the amateur modeller, as they provide all kinds of makeup options and facial features. You can move mouths, etc for speech and it's all state of the art... like Avatar. And we all know that 3D actors that often look more real than actors and are inserted into films or TV series.
The modellers I know in the forums are just creating for proper entertainment or, most of the time, for education or advertising products (think of those crazy things that cars and people do in TV adverts). Porno modellers do not publicly participate as I have not seen any questions or posting of their work. It would not be permitted by the manufacturer of the software.
Still.... 