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.
YMMV: Romance of the Three Kingdoms
The following relates to the work and all its adaptations in general:
His most Idiot Ball moment (claiming "I am too happy [in Luoyang] to think of Shu" after his surrender) was especially interpreted this way, as claiming to have any remorse towards Shu would most likely cost his head. As a matter of fact, he is also one of the few surrendered monarchs who died of a natural cause.
Badass Decay: In the first few chapters of the novel, Liu Bei displayed some serious fighting skills and was able to duel Lu Bu alongside his brothers. Later on, he became more of an Iron Woobie.
Broken Base: There's a camp who enjoys the story for what it is... and then there's another camp who's absolutely furious that Shu receives way too much Historical Hero Upgrade while in history they're not that virtuous or great, and other kingdoms who are more capable had their capabilities downplayed and thus often felt compelled to make statements about how the history is always the 'more right version'
Designated Hero: Liu Bei. To elaborate, he repeatedly abandons his wife and children, doesn't punish a hunter for murdering his wife to feed him, and also throws his own baby to the ground. And the book doesn't call him out for them because of Values Dissonance and his effort to restore the "legitimate" dynasty.
Ensemble Darkhorse: Ma Dai plays a small role in most of the book, but has the tendency to end up in pretty much every "Characters I want to see in the next Dynasty Warriors game" list. And voila, he did, for the seventh installment.
Ho Yay: Liu Bei is noted to sleep in the same bed as quite a lot of his trusted generals, brothers, or strategists. While this is a thing one does in ancient China to show respect, the novel also indicates that Liu Bei and Zhao Yun specifically showed great affection for one another, down to tearful farewells and, in one traditional story, singing poems to each other about "being joined as one body."
Simply, Cao Cao. He's the kind of guy who will recite poetry on the Yangtze, murder a nearby lackey who criticizes it, and then bury him with full military honors, all in the same scene. He's unfailingly polite to his guests, even when he's about to have them killed. He's unflappably cool, even after a defeat they'll be making movies about a couple thousand years later. The man is the original magnificent bastard.
Zhuge Liang, also.
Sima Yi reaches this when he gives his speech to Gongsun Yuan's emissary:
"There are five possible operations for any army. If you can fight, fight; if you cannot fight, defend; if you cannot defend, flee; if you cannot flee, surrender; if you cannot surrender, die. These five courses are open to you, and a hostage would be useless. Now return and tell your master."
Zhou Yu whenever Zhuge Liang isn't also in the scene. Puts on an elaborate Feed the Mole plot, complete with a drunken sword dance. Hands Cao Cao his greatest military defeat at Chibi.
Mainstream Obscurity: Its importance in the Asian literary tradition is hard to overstate, and you can just scroll down below to see the extensive list of derivative works it's spawned, to say nothing of the numerous references to it, its events and its character that crop up so frequently in Asian culture, yet like Shakespeare and other comparable western classics, when it comes to people who've actually read it, particularly outside of a school context...
Mary Suetopia: The Kingdom of Shu with Zhuge Liang as Prime Minister. All the peasantry are happy and well fed, taxes are paid on time and treasuries are full to overflowing, and people strive towards excellence in every facet of government. Hilariously, this was basically how Wei historically was under Cao Cao's rule.
Mary Tzu: Even though Zhuge Liang was quite a competent strategist and administrator in history, the novel escalated his skills to the point where every other strategist in the novel is forced to play second fiddle to his plotting, which approaches near-prescience. His lustre does begin to wear off near the end, though, as age catches up with him and he starts to make more frequent and costlier mistakes that get capitalised on more often by more dangerous foes like Lu Xun and Sima Yi.
One-Scene Wonder: Mi Heng. He only shows up in one chapter but his delivery of so much snark and of course his infamous "drumming naked" scene helps him make a lasting impression.
Values Dissonance: This is not modern America. Events such as the value of one's body, and relationships (valuing of one's sworn brothers over wives and children) will only make sense in the light of historical Chinese culture.
What an Idiot: He Jin could definitely qualify. After living through pretty much every plot by the eunuchs to make sure no royalty threatens their power, he receives an invitation to the Forbidden City. At the time, he is involved in a rebel plot and the eunuchs have eyes everywhere. In fact, pretty much every rebel warns him not to go. He brushes it off and decides to go anyway. So they insist on escorting him, well armed. Then, the guards tell him he must leave his guards at the door. He agrees, and proudly walks in. He, unsuprisingly, is surrounded by the eunuchs who hack him to pieces and toss his head back to his friends.
Lu Bu also qualifies. The man is, simply put, a naive fool. Seriously; he's swayed to work for Dong Zhuo in the first place, but that isn't the end of it. He's charmed by Diao Chan, and then later, goes back and forth between alliances because of what someone who wants to use him just happens to tell him. He slowly becomes smarter and craftier as time goes on, but that naivety still remains. His temper doesn't help either. The only thing Lu Bu had going for him was his incredible strength in battle, but even then, that just made more people want to use him, and that just led to a continuing string of Face Heel Revolving Door choices caused by his own naivety and gullible-nes. If it weren't for his sheer strength and skill as a warrior, he wouldn't really have gone anywhere in the Three Kingdoms period.
Zhang Fei certainly counts. He didn't put much thought into his actions, and just did whatever he wanted to regardless on the consequences. Case in point when he's supposed to be guarding the castle while his Oath Brothers are away. He's supposed to not take a single sip of wine, and also not beat his own men, and he even writes these very rules on the wall so that he won't forget. And what does he do? He drinks a ton of wine, and beatsLu Bu's cousin. What happens next is probably what you would expect: Lu Bu unleashes holy hell on Liu Bei's castle, and the only thing Zhang Fei can do is run away. He even tries to kill himself after this, though Liu Bei & Guan Yu stop him. So at least he's very sorry, but that still doesn't excuse what he did. Thankfully, he became more competent later.
The following relates to the Mitsuteru Yokoyama's anime adaptation:
Memetic Mutation: As mentioned in its article, Kaizo Traps are called "Koumei's Trap" after Zhuge Liang. The ultimate origin of this name, though, is from this adaptation. Specifically, when Sima Yi heard about Zhuge's dealth:
Sima Yi: Wait, be calm; this may just be another of Koumei's traps'.