Anti-Climax: "The Babysitter" is a classic case of The Calls Are Coming from Inside the House, but with a twist—the babysitter was Genre Savvy enough to call the phone operator, who traced the calls to the inside of the house and promptly warned her and the kids to get out of there while she calls the police. The man who was making the calls is arrested only a few minutes later.
Awesome Art: There's a very good reason those illustrations are the most memorable thing about the books: Stephen Gammell is a damn talented artist. If he wants to terrify the living crap out of you with his nightmarish twisted imagery, he will more than deliver.
Critical Research Failure: Many of the stories are listed in Schwart's notes as folktales when they actually have direct literary antecedents.
For example, "The Drum" is misattributed as a folktale in Schwartz's notes in the original edition; it's actually a barely modified version of "The New Mother" from the 19th-century English author Lucy Clifford's collection, Anyhow Stories.
"The Wendigo" doesn't much resemble the folkloric monster; that's because it's based on Algernon Blackwood's quite different take on the legend in his 1910 short story of the same name.
Ensemble Darkhorse: Harold is easily one of the most recognizable monsters in the series. Having a name and backstory certainly helps.
Fridge Horror: These are typically classified as children's books.
As mentioned under What an Idiot!, the family in "The Big Toe" cooks and eats a corpse's toe. What kind of people are these?
The ghostly woman from The Dream was probably right about the inn: Lucy's room has trapdoor shaped carpets and boarded up windows.
Nightmare Retardant: The stories in the final chapter of each book are "supposed to make you laugh, not afraid".
Also, in the video for "Clinkity-Clink" the wind noises. Wsstchwsstchwoo!
Older Than They Think: The Bus Stop. According to Mr Schwartz in the book's foreword, this story actually dates *to Roman times*. For the curious it's an adaptation of the Vanishing Hitchhiker legend.
They Changed It, Now It Sucks!: The books are being re-released to commemorate the 30th anniversary... with new illustrations. Many people who grew up being terrified by these books and their original, creepy illustrations are not happy.
And adding insult to injury for those who were never able to obtain personal copies of the originals, they have been taken out of print (including the more recent anniversary editions) and online prices are being inflated.
Rejoice! Scholastic Press still sells the original versions (the bowdlerized versions are published by Harper-Collins), and the price spike on used copies has subsided!
Ugly Cute: The illustration of the pale woman in "The Dream" .
The titular character of "Sam's New Pet" is actually pretty adorable in its own way.
Uncanny Valley: The illustrations never leave it. Even relatively innocuous ones like "The Babysitter" are extremely unnerving.
Even when something perfectly normal is drawn, it still manages to look really creepy.
What an Idiot!: The family in 'The Big Toe.' Their son pulls a big toe out of the garden, and the family decides to... cook it and eat it.
The Woobie: Mina of "Just Delicious." A sweet, timid little lady who's married to a cruel, bullying jackass, and yet she still tries to keep him happy with her excellent cooking. She accidentally eats his dinner one day, and is so afraid of what he'll do to her that she's willing to steal another liver —from a mortuary— to cover her mistake. And then there's an animated adaptation, which ramps up poor Mina's woobie-ness by actually showing the Domestic Abuse the original story could only hint at.