I guess the dark part(s) of the Earthquake episode would be how such a gentle giant wound up being treated like shit for "crossing" Vince McMahon and how such a horrible thing like cancer would take a loving family man from his family and peers far too early.
To me, that's pretty dark in my eyes. You have a guy who didn't party it up on the road or anything, didn't get hooked on drugs or alcohol, didn't sleep around on his wife etc. that was treated like shit in the long run all because he made a personal decision that allowed him to spend more time with his family. And even then, WCW goes and gives him to the lamest gimmicks imaginable. A man like John Tenta deserved a lot better.