In the late 1970s, ABC decided to cash in on the popularity of Addams Family reruns by getting the cast back together to make a crappy Halloween special and seeing if it generated enough interest to restart the series.
Okay. "Crappy" probably wasn't part of the original plan. But quality clearly wasn't one of their bigger concerns. The special they made was in bright, vivid color (which just doesn't work for these guys) and shot on video (which just doesn't give it the right atmosphere). Unable to recreate the original set (most of the props had been stolen when the first series ended), they settled for building an entirely less interesting one. Sure, there are graves outside, but the new place just doesn't seem ver spooky.
They brought in a guy who was actually a Munsters writer to do the script, and for a while when I watched this, I thought he was still secretly playing for Team Munster and trying to sabotage this show. But I came to realize that it's not really the script that's the problem so much as the directing and the editing. The timing is all wrong for most of the gags. The pace of the special is howlingly dull. A different director might have made this script work with a better set and a better budget. The cast was still in good shape - there's no reason why they couldn't have done a pretty good new series in the 1970s with Wednesday and Pugsley as young adults.
But, well, that wasn't the result here, and the new series wouldn't come around until the 90s. In fact, rather than having Wednesday and Pugsley as young adults, they brought in two new kids, Wednesday JR. and Pugsley Jr, to handle all the jokes Wednesday and Pugsley would have had before - it seems the producers were determined to make this pretty much the same show, with the same jokes, as it was in the 60s, only, well, not as good. Still, the special is fondly remembered by people who used to watch it before going trick-or-treating. A show doesn't have to be good to inspire nostalgia, just as books and movies certainly don't have to be any good to become cultural phenomenons.
Here's the first part, which should be enough to satisfy your curiosity. The rest is on youtube, as well.