Go to any comics related imageboard and make an original post and type in the magic words: "THEY TOOK OUT THE SQUID!" accompanied by the appropriate spoiler pic. The original poster will then see the resulting thread grow into a bitter, flaming hot discussion between fans fruitlessly debating on whether or not Zack Snyder's controversial decision was a good idea. The debates just parallel the regular discussions about Ozymandias' controversial decision!
Ask a group of Marvel fans who they like more - new Captain America (Bucky Barnes) or old Captain America (Steve Rogers) - then get out the marshmallows.
Then there's fans of lesser-knowns, such as Isaiah Bradley, John Walker, William Naslund, Jeffrey Mace and Scott Summers as Cap from an alternate future reality...
Even better, ask whether Civil War was idiotic and should be retconned and forgotten, or a legitimate storyline that should continue to leave its impact on the Marvel universe. The flames will fly, and the only thing that comes close to a consensus was that the event sucked (and that is a source of a debate between some factions).
Try and ask comic fans who a superhero's true love is. You will get a long, twisting thread of responses screaming that Catwoman is the person Batman is meant to be with or Wonder Woman is the only one who deserves him; declaring either that Jean Grey and Scott Summers are OTP or that people should move on and accept Emma Frost; or fighting over whether Peter Parker and Mary Jane Watson's retconned-away marriage can be salvaged in the future or is ruined. Then there's the heroes who don't have alternate potential love interests, who some fans will insist should not have any love interests at all (yes, even supposed untouchables like Clark Kent and Lois Lane). And don't even start considering the personality changes and deleted characters and relationships between Pre Crisis to Post-Crisis continuity if you're talking about DC. It is impossible to please everyone, no matter what you do.
Take a panel from any Big Two superhero comic, from any era, and ask fans what they think. You will be beset by arthouse snobs insisting that everything before the Modern Age is crap, Silver Age nostalgists complaining that a scene has the wrong character dynamics (or characters), Marvel fans whining about DC characterization, DC fans whining about Marvel narration, old school fans complaining about modern continuity, new fans whining about four-color artwork, people insulting thought bubbles, people insulting the lack of thought bubbles, people hating on a character, people hating on a different character, irrelevant complaints about the writer/arc/future continuity/past continuity thrown, etc, etc, etc. Superhero comics doesn't have a Broken Base. It has a shattered base where each shard represents one single fan's opinions.
DC fans have a division over the New 52 relaunch. One side loves it, one side unreservedly loathes it and all it stands for, and the Silent Majority likes certain aspects. Dan DiDio noted that most the hate comes from fans who have favourite characters replaced or benched. Wally West/Barry Allen, old Teen Titans/ Lobdell Titans, old/new Starfire and the Batgirls issue are notable fan schisms, with Earth 2, Power Girl's costume and Action Comics also inflaming fans. Tellingly, series that have been better received by fans have smoothed out prior schisms.