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.
Alternative Character Interpretation: Is Dan The Stoic or simply The Quiet One? How heavily was he involved with drugs? How long was he in juvie? Is he the Teen Anova of Sleepyside because All Girls Want Bad Boys, or do other students fear him due to his criminal past? Why does he never seem to want to hang out with his friends or confide in them? How close is Regan to Dan, and does Mr. Maypenny see Dan as a surrogate son/grandson? Is the reason he doesn't hang out with the rest of the Bob-Whites because he's envious of their sheltered, affluent lifestyle and doesn't want to create conflict with them?
Did Dan suffer torture by switchblades at the hands of his former gang?
Regan is always described as "wonderful" by the Bob-Whites, but how great of a guy is he really? He sends his nephew and one living relative to live out in the woods with a stranger, initially acts ashamed to be associated with his nephew (who has spent time in a juvenile detention center), does not give the boy proper clothing he would need for his job (which involves winter weather and rough terrain), and after the nephew proves himself, rarely spends time with him, and then, when he encounters a problem himself, runs off to another city with only a note giving a very vague explanation of his actions. It's worth noting that Dan has various chances to confide in his uncle about his troubles in The Secret of the Unseen Treasure and The Mystery of the Uninvited Guest, but he takes none of them.
Angst? What Angst?: Trixie and Honey never are deterred by the life-threatening situations they get into.
Dan was held captive by his former gang for two weeks, on the third floor of a hotel, in the middle of the summer, in room that did not have air-conditioning. The possibility of him being physically tortured with switchblades was hinted at, and the shaky circumstances preventing him from being tortured fell through, increasing its chances. He never expresses any emotion about this at all.
Jim rarely shows signs of a teenager who's lived with an abusive stepparent.
Canon Sue: Trixie can verge on this at times, especially in Mystery of the Emeralds. Any character who doesn't adore her at first sight is vilified, Trixie monoppolizes Diana's birthday trip for her own mystery and throws a tantrum whenever someone else wants to actually explore Williamsburg, which is treated as justified, most of her endearing tomboy traits are lost. She's taught herself to develop a "photographic memory", a character meets her and immediately declares that she's the most intelligent of the three girls, and anyone who disagrees with Trixie, even for the mildest of details, is portrayed as wrong.
In the same book, Trixie, who is from a middle-class farming family, is able to identify fake jewels with certainty before either of her two wealthy female friends, one of whom has grown up surrounded by precious jewelry, the other whose parents have recently acquired wealth and are avid buyers of ostentatious antiques and jewelry as a display of their sudden affluence. Both of them should have been able to identify the necklace before Trixie.
Designated Hero: While part of the series' appeal is that she is a realistic teenage girl, Trixie sometimes acts unbearably bratty, hypocritical, self-centered, smug, and excessively judgmental.
Die for Our Ship Dot Murray, a one-shot character from The Happy Valley Mystery, is often horribly demonized by the fandom, especially those at Jixemitri, a Trixie/Jim fan website. Dot has no dialogue at all, no seen interaction with Trixie, and even Trixie honestly admits that Dot is "swell." But Dot is crucified for the crime of being pretty, slender, and interested in Jim when he is single. Jixemitri fans sometimes create threads specifically to bash her.
Seen here is a thread where Dot is written to be sexually promiscuous so members can pretend to be book characters and take turns calling her names. Oh, and ableist-tainted bashing of people with eating disorders, implying they are shallow, vain, and selfish for daring to have body issues. What makes this slightly pathetic is that most Trixie Belden fans are of the older female variety, which means a bunch of middle-aged women are slut shaming a fictional character without an established personality, just because she got in the way of their oh-so-precious OTP.
Fanon Discontinuity: The last five books of the series are almost universally disregarded by fans, for the lack of meaningful character interactions, blantant inconsistencies with the rest of the series, and overall poor quality.
In Mystery of the Emeralds, she is outraged that a man yelled at her for trespassing. Though the man was rude to her (and is later revealed as a villain), he was perfectly within his rights to prevent people from trespassing on his property.
In The Black Jacket Mystery, Trixie mocks Dan (for his clothing, of all shallow things) to Honey the moment she lays eyes on him. He notices and takes offense, and is later rude to her, which offends Trixie. While Dan is no saint, Trixie was the person to begin the conflict between them, and despite the narration's attempt to justify it, she's the one who later continues the argument.
Unintentionally Sympathetic: Dan, in The Black Jacket Mystery. The audience is supposed to have some sympathy for him, but in his interactions with Trixie, he honestly comes across as an underprivileged kid who is being by bullied by his spoiled, entitled classmate. See Unintentionally Unsympathetic.
Unintentionally Unsympathetic: In Trixie and Dan's interactions in The Black Jacket Mystery, neither of them of them are portrayed as completely innocent. Trixie, however, is the main character, and it is obvious from the narration that the audience is supposed to side with her. But that's difficult to do considering these factors, especially during re-reads:
Trixie lives in a sheltered small town, with an intact, stable family, in nice farmhouse with farm property. Her father is the bank manager, her mother is a homemaker. The family is said to be poor, but they never face any financial difficulties or shortage of food or clothing, and they can afford to give four teenagers five dollars a week each (this was established in 1951. With inflation, that's over forty dollars per teen each week). Her closest friends are exceedingly wealthy for their time. Trixie is thirteen.
In contrast, Dan lived through the death of his father, and later on, the death of his mother, lived on the streets of New York City for a time, joined a street gang to survive, was arrested in a gang fight, and shipped off to live with his uncle, who he didn't know at all. The uncle, embarrassed to be associated with him, denied relationship to him, and shipped Dan off to live with a hermit-like gamekeeper who lived in the middle of the woods. Not only did this mean Dan was isolated from diverse human contact, but we later see that he was forced to walk long distances to reach the school bus stop (or get to anywhere) and was not equipped with the proper gear for rough terrain in winter, nor did he actually know the way. Why this arrangement was allowed is anyone's guess. Dan is somewhere between fourteen to sixteen when this is going. Granted, Trixie only knows about where Dan is living, not why, until the book's ending.
The very moment Trixie sees Dan, she points and laughs with her wealthy friends, mocking his clothing. He notices this and takes offense, and doesn't make any effort to impress them when they are introduced, which irritates Trixie. However, not only is it understandable to be cold toward a person who was openly mocking you, but on re-reads, the audience realizes that Dan probably did not have much other clothing to wear. Culture differences guarantee his city clothing would be viewed differently in a small suburban town.
When Trixie and her wealthy friend Honey go horseback riding, they notice Dan wandering around the game preserve where he works, attempting to walk home from school, wearing clothing that isn't adequate for winter or the wilderness. Honey offers to help him, while Trixie stares at Dan judgmentally, but Dan sullenly refuses Honey's help, expressing reservation about associating with the daughter of his employers (again, understandable in his situation). Trixie is angered by Dan's unfriendliness, and insults him to Honey as though Dan isn't there. This incident begins bad blood between Trixie and Dan for the rest of the book and verbal battles, including her accusing him of theft and vandalism based solely on circumstantial evidence, which brings Dan's uncle to dislike him even more (though Trixie isn't aware of this). All of this is in spite of three people, Honey, another wealthy friend, and family friend whom Trixie believes is Dan's grandfather (he's not), asking Trixie to make more of an effort to be nicer to Dan, at which she only gives a single, luke-warm attempt.
Trixie's actions and opinions unintentionally isolate Dan from his uncle, his guardian, and the few people who live within five miles of him, which includes Trixie's close friends. Some of this is Dan's fault due to his surliness in regard to Trixie and her friends, but he wouldn't have acted that way had she not begun deriding him the moment she laid eyes on him. However, if he had had someone to confide in with his problems, most, if not all, of the damage that took place during the story could have been avoided, and the villain certainly would have been caught sooner.
Basically, looking at the book from Dan's perspective, a sheltered, spoiled, wealthy girl who everyone loves continually belittles and insults him, destroys his chances of turning over a new leaf, ruins his relationship with his uncle, and makes false accusations against him, and leads to a dangerous criminal being able to go undetected. It's a wonder why he bothered becoming friends with her, let alone saving her and her younger brother's life at the end of the book.
What an Idiot: During Mystery of the Mississippi, Trixie and her friends are being stalked by a ruthless man, who unknownst to her, is a terrorist. What she does know is that a cohort of the terrorist has already nearly succeeded in bringing her and her five friends out to an isolated spot on the river, and they were only saved by sheer luck. So what does she decide to do? Go swimming in the hotel pool, alone, after hours, when she knows that she is in danger, without telling anyone where she's going, which of course, leads to the terrorist nearly killing her. Too Dumb to Live barely even describes such stupidity.