I rent the sixth season and find out that it's subtitled only in French & Spanish. My fluency & command over American English is fairly good and in most cases I don't switch on the subtitles. But in niche dramas like West Wing where a lot of sharp politico dialogues are spoken in quick succession, though written with the mainstream in mind, I found it difficult to follow (and I'm one of those crazies who tries to understand every spoken word). It beats me why the stupid producers didn't subtitle it in English, especially after carrying it for the first five seasons.
Update: I don't see a reason for this post to exist. It's an utterly useless observation, just a bit garnished. Hmmm..