I think that in S3 and S4 both Sam and Ellen bore no resemblance to the characters we were shown in S1. I found them to be more real in the first season, more like actual people, not caricatures thrown in for comic relief, which I thought was especially true of Ellen as portrayed by Beverly Garland: she was nothing like the supportive, caring Ellen Lane played by Phyllis Coates (even though with only got a glimpse of her).
Same goes for Sam's character. I loved Denis Arndt's Sam, because when we saw him interact with Lois it explained so much about her past and how she became the woman she was. I didn't get the same impression from Harve Presnell's Sam, even though he was more three dimensional than BG's Ellen.
The Kents were real characters and they were fleshed out, but we need to keep in mind that they had much more screentime than Sam and Ellen and the writers were able to develop them.
