As a fan, I'd like to use the example of The Brady Bunch. I adore the original series quite a bit. While its status as a classic series is still up for debate, it's hard to argue the show's "cult classic" standing. While the original series remains popular to this day, the subsequent spin-offs have not faired as well. They are really only of interest to die-hard fans such as myself. The best example is the 1977 variety series, The Brady Bunch Hour. The concept is puzzeling, to say the least. The entire cast was reunited for the variety series. Well, all except Eve Plumb who played Jan. For The Brady Bunch Hour, the part of Jan was played by Geri Reischl. Among Brady fans, she is commonly referred to as "The Fake Jan."
Now, I wouldn't say that the actors were old. 1977 was only three years after the cancelation of the original series. That said, the kids had certainly outgrown their early cute appeal. In fact, they had started outgrowing said appeal during the fifth season of the original series, which is exactly why Robbie Rist was cast as Cousin Oliver. The spin-offs never created the same magical spark the original series had, and still does. They were just entertaining enough to appeal to the most loyal of fans, much like the DeRita features from 1959-1965.
Following the short life of The Brady Bunch Hour, the cast reunited for several more projects including The Brady Brides, A Very Brady Christmas and The Bradys, a 1990 series that presented a more dramatic look at life in the Brady household. Although Susan Olsen (Cindy) sat out on the Christmas film, and Maureen McCormick (Marcia) was absent from The Bradys, it's Geri Reischl who will forever be the "CurlyJoe" in the Brady analogy. When it comes to the variety show, Reischl was good, or at least good enough, to help keep the Bradys alive just a bit longer.
If one really thinks about it, Geri Reischl is more "Curly-Joe" than DeRita himself was. The only real similarities between DeRita and the late Howard brother, was their weight and bald heads. Other than that, DeRita made no overt attempts to "be" Curly at all. On the other hand, during the nine-episode run of The Brady Bunch Hour, Reischl made every attempt to be as true to the "Jan Brady" character which Eve Plumb had popularized for five straight seasons. While her efforts were descent, Brady fans will always prefer the original cast members.
It's that way with the Three Stooges, as well. While fans can appreciate that Moe and Larry kept the name and act alive in the years following the deaths of Curly and Shemp, and can even find some enjoyment in the shorts and features produced in those years, it's really the work of the Howards and Fine that is the act's true legacy. If nothing else, it's always great to see Moe ad Larry together. The same goes for the Brady Bunch spin-offs, as well. While it was always fun to see the cast back together again, it has always been the original series that has kept the Bradys popular the past 40 years. Geri Reischl, or the Brady's "Curly-Joe," brought nothing new to anything with her casting. She was simply an adequet replacement needed to round out the Brady family. To many fans she will be remembered best as "Fake Jan." To a number of Three Stooges fans, Joe DeRita will live on as "Fake Curly."