Disclaimer: I am German and I actually saw and liked 30 Rock (in English) ;-)
As for 30 Rock: The problem with English shows on German television is that they are all dubbed. I won't say that they are doing a bad job (c.f. eastern european countries) but sometimes they are missing out puns and jokes which "can't be translated" without losing meaning. In the end this can make a funny TV show unwatchable.
On the other hand you will never (as in never ever) see an undubbed show on German television. People are used to watch it in German, so most of them might just never watch it again in either language.
I'm from OZ, and to be honest, I need the canned laughter when watching US comedy - because the humor is not obvious (eg. Will and Grace- canned laughter when a dog walks across the screen ... Ahh, Americans find that funny... Ok)
Now British humor? I get that without canned laughter.
I do. I watch American shows and films exclusively in their original version because of the really bad job they do with the translation. From time to time I catch the dubbed version by accident. Mostly I just cringe and make it go away.
seinfeld is a really good example for this. a hilarious show; someone watching the dubbed german version would never understand what's funny about it...
edit: s/Disclaimer/FYI/