Popular Mechanics has an excellent article of the dirty little secret of HDTV: that there are no true standards or specifications in place defining what exactly is "high definition TV". Because of this, the article's writer, Glenn Derene, writes, the quality of broadcast we get from providers, varies. Considerably.

For instance, compression techniques can differ, with fast action shows needing more updates than "talking head" shows. Compression can degrade with the faster shows, than the ones that are more "static", and with fewer moving parts. This explains to me why the news shows are the best looking shows on my HDTV.