This is one of those areas where I'm likely to find myself more concerned with how the question is asked than what the subject is about.
In other words, a question about accents wouldn't necessarily be out-of-bounds by default, but I'd hope it would be carefully crafted and somewhat researched.
I'm not a big fan of the Inglorious Basterds question as it is now:
Which accent has Brad Pitt adopted in the movie Inglourious Basterds for the role of Lieutenant Aldo Raine?
I'd be more accepting of the question if the O.P. at least at mentioned something about the character and the accent – for example, where is this character supposedly from? (This information is readily found here.) It might also be helpful to include a link so that those unfamiliar with the accent could have a listen.
Also, it's not very clear what the question is really asking about. What is the accent? It seems like any of these answers could be considered correct to some extent:
- An American accent
- A southern U.S. accent
- An Appalachian accent
- A Tennessean accent
- A hillbilly/redneck accent
- An Allegheny accent
But I figured that out just by reading the character's description in an IMDB database, and listening to 25 seconds of a YouTube clip.
It might be better to ask something more along the lines of:
I know the Aldo Raine character is from Tennessee. Does his accent seem accurately portrayed?
or, if the O.P. has something different in mind, be more specific about the question.