I've noticed that there are quite few cartoons I've learned existed thanks to comics ads, and, recently, the internet, that I never saw back then. It's either because I was too young to have remembered or cared to watch them, or it might have been that some cartoons were only shown on certain stations. A regional thing.
The Real Ghostbusters is an example. I remember the Filmation Ghostbusters pretty well... I think it was syndication on some channel in the afternoons. I did have a few of the Real Ghostbusters figures, but I don't remember seeing that cartoon at all.
I also learned a while ago that there was a Dukes Of Hazard cartoon, simply called The Dukes. It had at least some of the actors from the television series providing the voices, but I don't think I had ever heard of that cartoon until a year or so ago.