I am a native English speaker who has scant practice with listening to spoken German except via Internet radio and DVDs from Amazon.de. I have noticed that some shows at the same intellectual level and presumably using similar technical production facilities are much more difficult to understand than others.
My primary examples are Verliebt in Berlin and Das Büro. Neither has subtitles for the hearing-impaired, both make no intellectual demands on the audience, and the sound and video quality of each would seem similar. Yet Verliebt in Berlin is almost always directly intelligible (unless there is a vocabulary problem), but there are numerous scenes in Das Büro that even after looping cannot be deciphered (by me, at least), even when I have a clear sense of what is happening, or what the joke is.
I doubt that this is a matter of dialect, since the actors and writers probably come from all over, so what might be the key difference? Has anyone else noticed this disparity in German television or films?