What really wrecked Superman for me was in two stories.
Superman killing the Phantom Zoners made me desert the supertitles. Superman does not kill. That blasphemously bad mischaracterization meant to me that the Superman I idealized had well and truly died in the Crisis. This wasn't Superman but an imposter. Byrne apologists claim he was being innovative, breaking new ground. Well, he didn't hang around to deal with the consequences of his bad decision so that doesn't wash; more likely, he was poisoning the well for his successors. Also, I'm sure I'm not the only fan who left for the same reasons. Byrne brought new fans in due to his popularity, then he manages to diss fans by his stupid story idea which went too far to drive at least some of us away. Even Unca Johnny isn't that stupid: He knew darn well he was going to reduce the fanbase with that story.
Superman's dying in the Doomsday storyline made me desert comics altogether. I could always answer the critics who claimed comics promoted violence as a way of life by pointing to Superman to prove them wrong. But when the ilk like Punisher, Wolverine, and Lobo are so vastly popular, but Superman's sales were faltering and they actually killed him, I could not in good conscience continue to support a comics industry that had grown so disconnected from my values -- Values that were formed in no small part due to the influence of those comics when they actually stood for values in my youth.
For role models, I looked to my parents and teachers and Rabbis.
For entertainment, I looked to fictional characters. I love Superman very much, but my enjoyment of a chauvanistic (though charming) hedonistic macho man like James Bond, the oily con-man Stainless Steel Rat by Harry Harrison, or the manipulative trickster Sam in Roger Zelazny's LORD OF LIGHT, is unaffected by the fact that if I knew them personally, I would probably think them jerks. Not to get political, but I can enjoy watching RAMBO movies despite the fact Rambo represents a type of national attitude toward aggression that I despise. My enjoyment of Tarzan novels is not hindered by the fact that the characteristics Tarzan possesses, a willingness to do violence and adherence to the brutal Code of the Jungle, are really hardly admirable traits at all.
But I do agree with you - the period you're talking about, and the Death of Superman, which best typifies that very period, was ugly, not because characters are behave immorally, but because characters were rewritten into unrecognizeable, intellectually bankrupt creative abortions.
If someone made a version of the Stainless Steel Rat where he was turned into the galaxy's greatest model citizen who never performed zany extraplanetary jewel heists but instead helped grannies cross the street, I would be filled with respect and admiration for the character, but I would be filled with murderous rage toward the writer that did this to one of my favorite science fiction series, a misappropriation of the reasons that I (and others) loved the Rat in the first place, namely his rascally ways and inability to stay out of trouble.
(Part of the reason I also love the Rat is that the Esperanto translation done by Esperanto lover Harry Harrison, LA KORODIMUNA S^TALRATO, is the first book I ever read in Esperanto, so there's a degree of pride there, but I digress.)
But all the same, I understand what you're saying, CaptainKal.
Immoral behavior is unnacceptable in Silver Age characters not because of the deeds in and of themselves, but because it is wildly out of character and innacurate to how they have been portrayed as being, to the point where one wonders if the writers even know who the characters are. Superman doesn't kill. Ever. Period. Under any circumstances. Combine this with the marginalization of old-fashoined but imaginative superheroes by an irritating trend that was becoming ubiquitous, which appeals to the lowest common denomenator, that is as unoriginal and idea-barren as it is grotesque...and I feel exactly the same way you do, CaptainKal.