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.
Alternate Character Interpretation: There supposedly exists a poem version of the story where Bluebeard is a regular man, the bride is very selfish, and the room is merely an empty room for Bluebeard to gather his thoughts. The bride, not being able to bear the thought of her husband keeping secrets from her, opens the room, and when Bluebeard finds out, he merely divorces her.
This is almost certainly referring to the Edna St. Vincent Millay sonnet "Bluebeard" (here).
There is also an absolutely hilarious Soviet cartoon called "The Very Blue Beard" in which the Bluebeard gets to tell his own side of the story to a detective. One wife was fashion obsessed, the other health obsessed, the third believed in an open relationship - well, sorry, love, that's the way it turned out.
In case you're wondering, Brides #1 and #2 were literally Too Dumb to Live, and Bride #3 did poor Bluebeard in, and presumably made up to classic fairy tale to save face. He's somehow alive, however, since he is telling all this to the narrator.
Crowning Moment of Funny: The Catherine Breillat movie version has the story being recounted by two little girls. When they get to the part where the girl in the story marries Bluebeard, they argue, because they don't seem to understand what marriage entails. The younger girl at first insists that it entails the wife being cooked and eaten by the husband, than claims that it's something involving an ogress, than claims that it means that the husband and wife become homosexuals.
Crowning Moment Of Awesome: In "Mr. Fox", the bride keeps her head even when finding her husband-to-be's Torture Cellar, watching him kill another woman, and having said woman's severed hand fall in her lap. She keeps the hand, bides her time, and chooses to confront Mr. Fox about it at breakfast, when the rest of her family is with them. Instead of directly accusing him, she poses the whole scenario as a dream she had, which Mr. Fox responds with by saying he's glad it isn't true. Before he can run, she shouts that it is true, and she shows the woman's hand as evidence. And then her brothers and suitors stand up and kill Mr. Fox before he can escape.
Family-Unfriendly Aesop: Some versions (including Fitcher's Bird) give the moral "It's ok to betray someone's trust as long as you aren't caught."
Perrault ends his story with the moral that a woman sticking her nose in her husband's affairs will ruin a perfectly good marriage - even if said affairs include murdering countless women.
Fanon: Due to the popularity of a British pantomime by George Colman, Bluebeard was frequently depicted as Turkish or Middle Eastern throughout the nineteenth century. His last wife was given the Arabic name Fatima. The nature of the story makes this orientalization of the story rife with Unfortunate Implications by today's standards. Andrew Lang insisted that Bluebeard was European and objected to his illustrator including oriental elements in the illustrations for The Blue Fairy Book.
These depictions have since fallen out of favor, as the story is by and large no longer used in pantomime. More modern adaptations of the story (such as the Catherine Breillat film and the Bluebeard episode of Grimm's Fairy Tale Classics) have kept the characters and setting European. (Both adaptations give the wife European names - the movie names the wife Catherine and the anime names her Josephine.)
Fridge Logic: Why did Bluebeard murder his very first wife? No versions of the story are forthcoming with any explanation...
What Do You Mean, It's Not for Kids?: Perrault did not write Bluebeard or any of his other stories for children, yet they were commonly marketed to children for centuries. Bluebeard frequently appeared in fairy tale collections for children until the early twentieth century.