These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Ensemble Darkhorse: Grady Wilson began as a guest character —played by a different actor— and was then reimagined and eventually took over the show for a time when Redd Foxx walked. Aunt Esther (Fred's late wife's sister) first appeared in a second-season episode and essentially became a regular from that point forward.
Seasonal Rot: The final season has its share of problems including a Vacation Episode in Hawaii that features Fred and Lamont running for their life from jewel thieves, a multitude of guest stars and an especially bizarre episode centered around Fred (played by Redd Foxx) entering a contest to meet his idol... Redd Foxx.
Arguably, the marker for the rot is the end of the third season, when Grady took over for Fred due to Red Foxx's contract negotiation problems. After that, the plots began to get more divorced from reality, the celebrity cameos became more common and the dreaded episodes with a message started getting made.
Some fans will argue that part of the problem stemmed from the overhaul in the production staff, replacing the original black writers and producers with Jewish writers and producers, causing the series to lose it's original authentic urban vibe, and turn into just another standard sitcom.
So Bad, It's Good: As Sanford and Son progressed and rose higher in the ratings, Foxx used his newfound clout to force the producers into hiring his old "chitlin' circuit" colleagues (most of whom were NOT trained actors, and it showed) for roles on the series leading to Brother Chuck moments in the second season when sensible Aunt Ethel (another of Elizabeth's sisters played by Beah Richards), Slappy (Fred's original foil) and Officer Swanhauser (Smitty's original partner played by prolific sitcom director Noam Pitlik) were written out and replaced with over-the-top counterparts. However, the broad antics and occasional wooden line-readings are part of the charm of the series, and Redd Foxx picked up the slack admirably when needed.