When people say "the worst comics ever," they usually mean worst in quality, not impact. Take, say, Reagan's Raiders. (Please.) Piece of shit, but no one cared. That's the way it goes; the stuff no one likes, no one remembers or emulates.
The converse is also true: that which is liked is remembered and emulated. And, in the case of the two worst series (in terms of their impact on fanboys), obsessed over.
I speak, of course, of Marvel's Official Handbook of the Marvel Universe, and DC's Who's Who. These are the legendary profile books, chronicling the complete history of their respective universes at the time of publication (the mid-'80s). Everyone who's anyone (and some nobodies as well) is represented. Periodic updates expanded them as well. In what must be the most gratuitous entry of all, the final issue of ALF contained as Handbook entry for the feliphagous alien. (Yes, I still have it.)
The books are obviously labors of love. The late Mark Gruenwald famously burned the midnight oil (and several assistant editors) putting together the OHOTMU. Who's Who was possibly the most ambitious archival project in comics history prior to the Grand Comics Database: an attempts to codify and clarify the post-Crisis DCU and its history. And they're certainly impressive in their level of detail; each entry contains vital statistics, origins, significant events and esoterica, all forming a biography as comprehensive as that of any real-life figure. The fan given to flights of fancy might imagine them to be imported directly from the files of Marvel's Watcher or DC's Monitor (now THERE'S a Superhero Showdown).
Perhaps that's the problem. Ay, there's the rub; the handbooks are a little too real. They create a vivid image in the reader's mind, but also a tight one, like a jigsaw puzzle. Every piece must fit. Shared universes work best under looser conditions, like a jazz combo, each artist free to compose his own riff on the basic theme, and take it in whatever direction he chooses. Stories bound to the rigidity of a handbook entry are rote and lifeless, like a caged bird with its vocal cords cut.
Fanboys who live and die by the handbook also raise the loudest and most impotent stinks when a story comes along that *gasp* doesn't go by the handbook. Ironically, the stories that contradict or change the stated entry in the largest ways are the easiest for the fanboys to get over. The cumulative effect of years of "he's not REALLY dead" retcons, perhaps. But violate the handbook in tiny ways, and prepare thyself for a shitstorm. Forget that Nash the ant died in Avengers 93, and include him in your story? Never knew that Dr. Light is allergic to shellfish? Show Hawkeye loading his glue arrow with Acme brand when the entry clearly states he uses Elmer's? Then you're a stupid bastard, and your editor is even a stupider bastard. Your first, last, and only job is to abide by the rules and events set down in stories written before you were even born, as codified in an archival project you've probably never read.
Incidentally, the reason so many large handbook infractions were overlooked is because the writers learned that fans would go berserk if they didn’t include long recaps and explanations for everything in their stories. This led, in most cases, to continuity-dense storytelling that required on-page flow charts for new readers to understand. Eventually, there came a backlash, most famously exemplified in Marvel storytelling in the Jemas/Quesada era, where almost no attention was paid to even the basics of consistent characterization, so that we had comics where She-Hulk destroyed a small town in Idaho and slept with the Juggernaut in Canada in the same week. (No, that wasn't hyperbole.) And that leads us to the false dichotomy of today, the turf war between the all and nothing camps that flares up every nanosecond or so on the Internet.
I don't advocate a completely anarchic approach to continuity, but I do think the handbook freaks need to remove themselves from the discussion. They're not doing anyone any good. Bottom line, the handbooks are bathroom reading, popcorn chicken, some other metaphor for the fun but inconsequential. In an age when even the Bible's canonicity is up for grabs, unclenching is a good thing.
I don't have much of a solution for the "continuity" problem, but I try to comport myself to two basic rules, both stolen from somebody else. The first comes from Official Good Buddy Jim McQuarrie, who holds that the continuity for any given story is what the story says it is. If it ain't mentioned, it ain't important, and if it contradicts, it contradicts. Fiction is large; it contains multitudes. The other is from Dan Slott's first volume of She-Hulk, the "use your fan powers for good" speech. I think a good deal of stress on all sides could be sides if more fans could try to slip into No-Prize mode when they see a contradiction they can’t live without an explanation for, and come up with one on their own. I do so all the time; it's fun.
Or, if all else fails, a wizard did it.