If you go to Ebert's wikipedia, you can almost miss the link to the screenplay he wrote:

https://en.wikipedia.org/wiki/Beyond_the_Valley_of_the_Dolls

This was co-produced with Russ Meyer, who basically made a bunch films which are as close to porn as you can get without being technically porn. He also made a ton of porn films as well. I haven't seen any of them, but many are now cult films. It feels debatable that he intended these to become cultural relics.

https://en.wikipedia.org/wiki/Russ_Meyer

I was surprised to see Roger Ebert was involved in that film! Gene Siskel, his long time partner, rated Valley of the Dolls 0 out of 4 stars, which is funny.