For movies, there are trailers/commercials, if people see that there is something they deem immoral, well then no one is forcing them to watch that movie. In the same vein, if the filmmaker is worried about people thinking the movie isn't ethical, then they don't have to make it.
It's simple really. . .unless you meant something else.
I think (s)he means the rating system (G, PG, PG-13, etc...). I think that this isn't necessarily the biggest problem for the entertainment industry post-state (intellectual property comes to mind). There are plenty of private blogs that review movies and come up with their own rating system, which often gives moviegoers a more detailed understanding movies content than the MPAA's one letter rating.
I think this would have been (as is often the case) a more difficult problem pre-internet.