How to grade kosher movies

I recently watched a really good movie. It is based off of a specific battle in world war two. It has a lot of violence and its a real thriller. There was one very not clean scene which I skipped – there is no question that watching that kind of thing is assur.

I love watching a good movie, but I hate when it gets dirty. I am wondering what people out there do. Do you watch movies at all? If yes, what will you not watch?

Dont start the whole, PG13 vs R thing because al pei Torah there are PG13s that are worse than R ratings. So you really need to judge it on a case by case basis. What is considered dirty and prohibited by the Torah? What is clean?