Andy Griffith has said in interviews that he progressively lost interest in the series and by the last season was mostly phoning it in. I agree that the show was never the same once Don Knotts left and it went color. I never have interest in those episodes.
Regarding the 'gay' theories:
Howard Spraig - Gay as a picnic basket.
Aunt Bea - Dyke city (and according to some, recently re-incarnated in the form of Rachel Maddow).
Apple
Rachael Maddow is more of a man than anyone on these boards.