These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Award Snub: They have yet to be inducted at the Rock and Roll Hall of Fame. But at least the 2009 Brit Award for Best Live Performance was won (deservedly), and in 2011 they got their long overdue Grammy (Best Metal Performance of 2010, "El Dorado").
Big Lipped Alligator Moment: The upbeat and happy istrumental section in the otherwise dark and depressing "The Man Who Would Be King".
Covered Up / Hate Dumb: Janick Gers wrote the riff that opens "2 Minutes to Midnight" for a song by his previous band White Spirit, called "Midnight Chaser". Adrian Smith, a friend of Gers, borrowed the riff with Gers' permission. People constantly bash the way he plays the riff live, failing to realize he wrote the riff, and the way it's played by him is how he plays it on the White Spirit song.
The song "22 Acacia Avenue", which is sub-titled (in the original liner notes only) as "The Continuing Saga of Charlotte the Harlot" which was the name of a song on their debut album.
Dork Age/Fanon Dis Continuity: The only albums which don't fall in this are the ones going from The Number of the Beast to Seventh Son of a Seventh Son. Otherwise:
No Maiden existed before Bruce Dickinson arrived. (Denial of the Di'Anno era)
No Maiden existed without Adrian Smith and Bruce Dickinson (Denial of the Blaze Bayley eranote note the "and"; that means No Prayer for the Dying and Fear of the Dark, which had Dickinson but not Smith, are not included in this definition)
No Maiden existed after Adrian Smith left (Denial of everything post-Seventh Son of a Seventh Son... sometimes including the four albums in the Turn of the Millennium)
Fan Dumb / Misplaced Nationalism: While Maiden's fandom is not so bad, go to any YouTube video of "Alexander the Great" and there will be a Flame War between Greeks, Macedons and nearby Balkanic nations. Best summed up in this comment:
There's also a large number of fans who consider Powerslave to be Maiden's best album.
Misattributed Song: No, they didn't do covers of "The Ripper", "The Zoo" nor they have a song called "Silver Wings"! And "Sabbath Bloody Sabbath" is sung by Bruce Dickinson but it's NOT a song of the band. Neither are every song which Bruce did outside of Maiden. (Read: His solo career.)
Back in 1982, Maiden put out a little song called "The Number of the Beast". Based on either a Nathaniel Hathorne story or a nightmare Harris had. To this day, many people still think they're evil Satanists.
Another victim of this is Blaze Bayley, who, despite his excellent solo career, will always be remembered as the Maiden singer who tried to replace Bruce Dickinson and failed.
Nostalgia Filter: Appliable to their fandom. Despite all (or at least, most) of the newer material being as awesome as in their "golden years", and despite having the same ol' lineup (along with Janick Gers) of that time, most fans will always prefer The Eighties' material over their new work. Sometimes without having heard the newer material, or hearing it while thinking in the Good Ol' Times. A pretty big part of the issue is that the band underwent somewhat of a Genre Shift after Blaze Bayley left and Dickinson came back, and went in a more Progressive Metal direction, which is really ironic, since "Rime of the Ancient Mariner" still remains as the longest song in the history of Iron Maiden, (The longest song of The Final Frontier, according to reports, is 11 minutes long) and Maiden always had a prog-metal feeling even in it's heyday. (Seventh Son Of A Seventh Son, anyone?)