Sometimes, the noblest of ideas end up failing due to poor execution, and the final product becomes so bad (How bad is it?), that no one wants to admit it ever existed.
Producer Whitney Ellsworth, who was also an editor at DC Comics, wanted to create a series similar to the successful Adventures of Superman, but with dogs, albeit people in dog suits. In 1958, Ellsworth produced a pilot for the Adventures of Superpup, using the dog-costumed actors and puppets. After you watch this sample, you might begin to wonder if Ellsworth should've considered animation..........
Three years later, Ellsworth tried again, this time with the original pilot for the Adventures of Superboy. That pilot didn't sell, either, but ultimately was released, as was Superpup, on video. I actually had the Superboy video at one time, and later traded it, but if I can find it on YouTube, it'll eventually turn up here. Superboy, of course, would finally become a series nearly 30 years after Ellsworth's version, and has recently been reviewed on my other blog, Saturday Morning Archives.