Yeah, the unnecessary clams were always my one complaint about "Genesis," too. But watching it again a few weeks ago, they didn't bother me as much. Maybe it's because "Genesis" was the best "Who" I'd seen in months.
I've been rewatching/listening to the entire series in order at the rate of an episode a weekday. I started in November 2013 and I'm currently in the midst of "The Seeds of Doom." Over all these months there's been only one story that I didn't want to finish watching...yes, it was "The Web Planet." There's some great character stuff in the first episode but unfortunately five more episodes follow that one. "The Celestial Toymaker" was also a hard one to take.
I consider Troughton's worst to be "The Dominators." The sheer insanity of Zaroff's plan to destroy the Earth purely for the scientific achievement saves "The Underwater Menace" from last place. Pertwee's worst includes "The Mutants" and "Colony in Space," although "The Three Doctors" might qualify if it didn't have three Doctors in it. So far, "Revenge of the Cybermen" and "The Android Invasion" are at the bottom of my Tom Baker list. They'll have company soon.