In 1969, Hanna-Barbera Productions hit paydirt when they aired the Joe Ruby/ Ken Spears-created cartoon Scooby-Doo, Where Are You? The show was such a hit that the formula would be copied again and again, often by Ruby and Spears themselves. We all know everything there is to know about Mystery Inc., so I’m going to reminisce about the lesser-known copycats (or dogs, in most cases). Following are brief synopses and categorized comments on how well…