For many episodes we have noticed the same thing. I DO have a waveform monitor in my house (Tektronix 528A), but haven’t been interested enough to check out 30 Rock with it. However, the show definately has low density, weak contrast and a muddy image – as if it is produced at a less than typical IRE level. I have always assumed that it is an artistic choice of someone in the director of photography office, but I cannot imagine why they would make such a strange choice for the “look” of the show. From what I have observed, it is about the same matter in both HD and SD. We are on Comcast cable and usually watch the show in HD.