Many films achieve effects by presenting speech with the speaker off-screen, or with the head turned away, presumably for artistic reasons. It is arguable that the art is not well served if the accompanying dialogue is unintelligible to a sizable section of the audience, but you may expect some difficulty in comprehension when this happens and it is not unlike watching a film in a foreign language.
Ed – how right he was in seeing how many people are not actually hearing the artists work. People send us emails at Blamey & Saunders Hearing, or come into the clinic, on this very issue, every day.
Note, that my Dad was very deaf, and his hearing aids were probably not really powerful enough. Also, this was some time ago, and good quality hearing aids have improved hugely in the last few years.