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: Zagor, Evil Warlock seeking to rule all of Allansia and plunder it's treasures to add to his collection on Firetop Mountain? Or a Designated Villain that only wants to be left alone? Were the heroes that killed him each time he was revived doing so for the greater good of the world, or solely seeking treasure for themselves?
The tie-in series of Novels depicts Zagor as a reasonable if reclusive character, and certainly not a villain. However, by the time Return to Firetop Mountain was published, he was rewritten as a pretty standard Evil Sorcerer.
Anticlimax Boss: In Daggers of Darkness, the main character is slowly dying from a scratch by a Death Spell Dagger. To break the curse, he must put the dagger in the hands of the man who ordered the hit, the evil vizier Chingiz. You eventually do so and Chingiz then keels over, having been stabbed in the back by his own villainous daughter. You don't fight her either, as the magical throne she's on disintegrates her and her pet ogres for attempting to spill blood in its presence.
Broken Base: Any gamebook made by the author Jonathan Green falls under this trope. This is due to his books containing a forced linear path, multiple instant death scenarios and unforgiving Nintendo Hard battle encounters.
Despite being one of the "big two" of Fighting Fantasy (with Steve Jackson (UK)) Ian Livingstone also has a big broken base. Many fans also accuse his books of having a cheap forced linear path, shallow gameplay that centers on gathering as many items as possible and random deaths.
Ending Fatigue: Caverns of the Snow Witch has you fight the Snow Witch halfway through. Then you spend the rest of the book gallivanting around the world to cure yourself of her curse. This is because Caverns of the Snow Witch was originally a half-size adventure written for a magazine. When it was released in book form, the "Part Two" portion of the book was added in order to bring it up to full size. Interestingly, this has the odd effect of giving you both styles of Fighting Fantasy: Dungeon Crawler, as seen in Warlock of Firetop Mountain, Temple of Death, and Deathtrap Dungeon; and Open World, as enjoyed in Star Strider, Creature of Havoc, and Sword of the Samurai — the first half of Caverns is the leadup to, and traversing of, a dungeon, while the second half is the slightly more linear/roleplay-focused open-world segment.
Evil Is Sexy: Just about every female villain in the whole series.
Germans Love David Hasselhoff: Fighting Fantasy was out of print in the UK between 1995 and 2002 after the original British publishers cancelled the series. The books were so popular in France that they still remained in print for all of that hiatus.
Of particular note is Beneath Nightmare Castle, which also had some genuinely disturbing monsters, and a scene in which the player has to slaughter a gang of children armed with knives. Many of the deaths the player can suffer also come under this trope. Beneath Nightmare Castle was notable in that they couldn't print one of the illustrations drawn for the book — namely, that of a woman with tentacles emerging from her mouth — because it was deemed too disturbing for children.
The Problem with Licensed Games: There were a few text adventures based on books from the series and a PS1 version of Deathtrap Dungeon, all of which were pretty execrable.
They Wasted a Perfectly Good Plot: Night of the Necromancer, where the main plot is that the player has been suddenly murdered, then returns as a ghost and has until dawn to find out why they were attacked and take revenge. At several points, particularly the parts of the book set at the gateway to the afterlife, it is strongly implied that once the character has reached this objective, they will pass on. Two paragraphs before the end, the character is Hand Waved back to life, and the typical "good" ending ensues, as opposed to the more interesting idea of the "good" ending being the character passing on.
In Deathtrap Dungeon, when you are forced to kill Throm The Barbarian Warrior, whom you have befriended, in self-defense after he becomes a drugged and mind-wiped slave.
In Night of the Necromancer, your reunion with your sister, which describes her attempting to embrace you despite the fact you are a ghost. Made even more tragic if the priest arrives and casts a exorcising spell midway through your conversation.
If you choose to kill the giant in "Scorpion Swamp," and you then return to the same area, you can see the giant's wife weeping over his body. She only looks at you sadly, and the narration says that the guilt forces you to never go back to that place if you can help it.
That One Boss: Razzak, the Big Bad and final enemy of Crypt of the Sorcerer, if he hits you twice in a row, he wins as you are enslaved by his power. And given his SKILL score (12) and STAMINA score (20) it's nigh-impossible to win normally.
Someone actually did the math and concluded that, provided you have Skill 12 and Stamina 20+, your chances of winning are exactly 5.5%.