I live in the Netherlands, where both National Geographic and Discovery Channel are available on television. In general, I enjoy watching their programs. In particular, those about History, Archeology, Wildlife, Ocean Life and Natural Phenomena. My impression is that these types of programs are "genuine," i.e., the documentary makers really want to inform the viewers, and producers don't ask for falsehoods to impress the audience and improve ratings. (But I might be wrong about this!)
On the other hand, both the National Geographic and Discovery Channel broadcast programs that are obviously fake and sometimes even nonsensical. A few examples are: "Chasing UFOs", "Ancient X-files", "Ghost Adventures," "Help! My house is haunted," and "Alien encounters: fact or fiction." I also recall a program in Shark Week in which it was claimed that once a yacht (mentioned by name) in trouble after a storm was circled by great white sharks, who suddenly fled when a megalodon appeared. Later, it was admitted that the story was 100 percent fake. Megalodons have been extinct for millions of years.
Why do National Geographic and Discovery Channel broadcast these programs? Surely, they must have a panel of scientific experts who object to the contents on the grounds that the programs contain fake information. Furthermore, frequently broadcasting fake content can easily tarnish the reputation of the two channels and their higher-quality programs.