History YMMV / UnsolvedMysteries

* AccidentalAesop: By a ways of ValuesDissonance, plenty of older cases show why simple everyday errands, such as going to the store on foot, buying a soda from an isolated vending machine and especially a trip to an ATM, should ''never'' be done at night.

** Tom Mcfall, father of Kurt Mcfall - a young man who was found dead at a beach, miles away from where his car was parked, shirtless and without his shoes, and covered in small bruises and abrasions - insists his son was murdered by a religious cult, even bringing forth a witness (whose identity is not revealed) to say that Kurt knew damning things about the group that could potentially land the leader in jail. We aren't really told anything about the "cult", and the man who leads it seems like a perfectly normal man. Furthermore, several clues point to the death being entirely accidental. Several beer bottles were found around Kurt's abandoned car, but his father claims he didn't drink and the coroner found no alcohol in Kurt's system. However, you digest beer fairly quickly, and the body was reportedly in very good shape when it was discovered, so Kurt couldn't have been dead for very long. The beach was notorious for it's treacherous, craggy cliffs. It was also a hot night which might explain why Kurt was missing his shoes and shirt. It's entirely possible Kurt merely fell from one of the cliffs and injured his head. Combined with the alcohol, this would have made it difficult to swim, leading to his drowning. The so-called cult leader sounds perfectly reasonable when he points out that Tom sounds less like a father crusading for justice and more like a man who wants someone to blame for his son's untimely but explainable death.

** The second reason is that the TrueCrime genre is much more popular in 2020, so there is a higher chance that viewers will be familiar with the case in question, not to mention that said viewers have access to the Internet and can factcheck details about the case from other sources.

* ReplacementScrappy: Dennis Farina, and really anybody who isn't Robert Stack, who unfortunately died in 2003. Strongly averted by Stack himself (there were narrators before him such as Raymond Burr and Karl Malden) thanks to his haunting narration (adding a certain amount of pathos to what may have been otherwise mundane stories), which was completely different to the other hosts.

* TheyWastedAPerfectlyGoodPlot: While the series profiled a number of well-known historical mysteries, many fans have expressed disappointment that they never did a segment on the JFK assassination. The production team addressed this years later, stating that the story had been profiled enough that UM's airtime would be better spent on other things.

** Robert Stack sometimes used the term "retarded" when referring to any person in the show that was mentally handicapped. Back then, this was the proper word, used by doctors, and considered to be a sympathetic, kindly description, replacing "moron" or "idiot" (which had once been non-offensive medical words as well).
* TheWoobie: Charles Holden. Imagine experiencing a life-threatening altercation with a hitchhiker, finding your mother brutally murdered, and then being in a police interrogation room accused of your mother's murder...ALL IN THE SAME NIGHT. It is a wonder how the man can still stand on two feet after going through such a thing.

** Adam Hecht disappeared after taking in a homeless man named Tony as a roommate, and his wealthy and privileged family notes he always had a particular empathy for the homeless community. While many think Tony killed Adam and disposed of the body, others suspect Adam may have dropped from sight to live as a homeless person after being disillusioned with his family's lifestyle, and they may even have known about it but didn't tell anyone one of embarrassment. There's also theories that Adam suffered from some mental illness, was having a mid-life crisis, or may have been a closeted homosexual, and that his efforts to cope with any of these led him to make contact with someone who killed him.

* FranchiseOriginalSin: A growing criticism of the 2020 Netflix revival is how the show ignores important information to push a narrative and/or sensationalize the mystery in question; for example, the first episode theorizes that Rey Rivera's death was a homicide by ignoring the FBI's diagnosis of Rey Rivera's mental health and by falsely claiming that Stansberry silenced potential witnesses with a gag order. It should be noted that the original version of the show had the same problem as well (e.g. The segment on Shane Stewart and Sally [=McNelly=] claimed with questionable evidence that [[SatanicPanic a Satanic cult murdered them]].), but there are two reasons why this flaw is more obvious now.