Despite how easy it is to criticize, critics (think Roger Ebert) have a hard job of it. They need to be as fair as possible in their assessments not just to gain and maintain credibility in their audience's eyes, but also because it can completely overshadow and ruin the review itself as a work.
Granted, critics are (probably) human and have pet peeves or favorites, and good/bad performances and dialogue are certainly open to criticism, but when these feelings get out of hand and leak into the review, things get worse.
If the critic has a strong bias against or in favor of a genre, style, director, actor, or what have you, and they allow that acerbic vitriol or blind admiration to fill their review, they're driving a Bias Steamroller. The review often stops being about the work and becomes about the element that inspires the bias; essentially boiling down to "I love (or hate) A; since work B has A in it, I love (or hate) work B; therefore you should (not) watch it."
This may be because they hate a particular trope or just like hating in general. Then again, they may be a fan of the series/franchise/creator and, out of loyalty, never fail to give the most glowing of praise. In any case, the damage to the review is such that it becomes too biased to be useful or insightful. (When a reviewer does this, people tend to ignore it, when fans often use it, it becomes a justified use of Don't Like? Don't Read!.)
In some of the worst cases, the reviewer may fixate on a particular thing they liked or disliked and give the impression that they might actually not have seen the work in question. And there are times where they actually haven't seen much of it. More honest reviewers will at least admit to their biases up front and acknowledge that any review is going to be slanted - if a reviewer says they think boxing is the most boring sport in the world, Sylvester Stallone is the worst actor in history, and Philadelphia should be erased from the map, the reader will realise they aren’t going to be able to give Rocky a fair shake and proceed on that basis when reading or watching the review.
Part of the reason this trope exists is that a review that accurately informs the readers about a subject's objective qualities, and allows them to make an informed purchasing decision, can be very boring. A hugely biased review, by contrast, may not be useful qua review but may be entertaining enough to keep the audience coming back. However, this does become an issue when combined with Reviews Are the Gospel, where said audience ends up dismissing a work because of a critic's personal hangups rather than any actual lack of merit.
Note that this happens a lot outside of media criticism. Because it's just easier to remember particularly noticeable or dramatic experiences and events, this routinely happens in both positive and negative ways to people like politicians and celebrities.
Compare/Contrast Unpleasable Fanbase.
Peruse the Ghetto Index to see examples of when many critics develop a bias against entire genres.
Examples (sorted by medium being reviewed):
- Bennett the Sage has made it quite clear that he does not like anime revolving around cute characters, and tends to be more negative when reviewing them.
- That Dude in the Suede had a bit of a textbook example with his "Suede's Pokémon Journey" episode discussing the Pokémon episode "Ditto's Mysterious Mansion''. Initially, he gave it an "F / Dark-Ball" rating simply because of the scene where Team Rocket bullies & threatens Ditto into having his shapeshifting powers work properly, which he felt hit too close to home for him and likened it to abuse.note Later, in a retrospect video discussing his goofs-&-errors in the videos, he does acknowledge he was too harsh with the episode since he did let his personal feelings cloud his judgementnote and gave a more forgiving-if-average "C / Great-Ball" rating.
- In general, the "Subbing Versus Dubbing" debate is filled to the brim with this. It's not uncommon for many anime reviewers or fans to take one side of the issue and only watch & review anime in their preferred way and not the other. And when they do, they frequently criticize the other version simply because it's not what they are accustomed to.
- Atop the Fourth Wall host Linkara is decidedly not a fan of anti-heroes in comics (mainly Nineties Anti Heroes, he's a bit more forgiving of those he perceives as having more depth and nuance). He primarily views superhero comics as escapism (not that he has a problem with them tackling serious subjects or challenging the viewpoint of the reader) and really thinks that anyone deserving of the title "superhero" should at least be trying to take the moral high road in any given situation. This can sometimes cause him to be overly harsh to Marvel comics vs. DC comics because DC doesn't have nearly as many anti-heroes, whereas Marvel has several and even has previous boy scouts like Cyclops become this. This bias also colors any review of any Darker and Edgier comic. He also really hates it when superheroes are killed off, but understands why it happens in some cases.
- Movieguide.com identifies its Bias Steamroller right up front, not trying to pretend it doesn't have one. It reviews films from a fundamentalist Christian perspective; for instance, they criticize The Golden Compass for its "strong pagan themes".
- Roger Ebert:
- He considered movies where young children are apparently unfazed about committing serious acts of violence to be "morally reprehensible." This was a major reason why he was not a fan of the Home Alone series, why he only gave Kick-Ass a one-star review (in contrast to most critics), and why he tore apart The Powerpuff Girls Movie.
- Ebert has expressed regret for his previous bias against the Spaghetti Western genre, particularly for how it drove him to give The Good, the Bad and the Ugly a 3-star score despite writing what he acknowledged was a 4-star review.
- Ebert's disdain for video games led to a noticeable bias against movies based on or inspired by Video Games. When asked about not reviewing Scott Pilgrim vs. The World, Ebert admitted to the bias (and a writing sabbatical). He added that he was still able to sleep despite not reviewing the movie.
- While guest hosting on Siskel and Ebert, Ain't It Cool News founder Harry Knowles panned SLC Punk! because he disliked the star, Matthew Lillard. Ebert, who praised the film, made this trope rather blunt when summarizing their takes at the end of the episode. Knowles was not invited back for another episode.
- The Academy Awards had to put "Best Animated Feature" up as a category due to the many times this caused a very well-regarded animated film to not be elected Best Picture on account of it being animated.
- Doug Walker in recent years has become known for his personal biases getting in the way of his various Nostalgia Critic and non-NC reviews. While some of these thoughts are understandable, they also cause him to suffer from a bad case of Opinion Myopia that affects how he approaches other works.
- He loathes the Disney Live-Action Remake films. While a lot of his criticisms of those films are reasonable and valid, he is also known for being very harsh towards them, often struggling to say anything positive about them. Whenever they are brought up (even the more generally liked ones such as The Jungle Book (2016)), he regularly bashes them, often getting sidetracked by his own ranting. Even viewers who otherwise share his dislike towards the remakes think he goes too far & is too harsh with them.
- He always had a dislike for the Star Wars Prequel Trilogy, which affected how he viewed many Prequel-Era Star Wars properties. In fact, during his “Disneycember” review of The Phantom Menace he stated that not only does he not understand why some Star Wars fans like the films, but he also said that he thinks they are naive and/or simply in denial & should admit they don’t like them. This unsurprisingly did not sit well with his viewers. Similarly, for years he refused to watch Star Wars: The Clone Wars despite fans clamoring him to do so, even admitting he thought it'd be pointless to do so.note He also gave a negative review towards Obi-Wan Kenobi simply because he felt it was too much like the prequels in his eyes.
- Perhaps the actor he hates most is Matthew Broderick... not for anything bad Broderick had done, but simply because he rubs him the wrong way. He either dislikes or outright despises every role he does, which sometimes bleeds over into the films the actor appears in, even stating he could barely tolerate him in Ferris Bueller's Day Off and that his role as Simba is one of the reasons he found The Lion King (1994) to be (somewhat) overrated.
- At the other end of the spectrum, Doug did a review of the infamous Spongebob episode "A Pal for Gary" as part of his "Dark Toons" show. He is one of the very few reviewers to give the episode a glowing review, simply because he likes darker cartoons and more mean-spirited humor. Many of his viewers, particularly those who are Spongebob Fans, felt he was far too lenient towards the episode.
- Troy Patterson of Slate made no attempt to hide his disdain for the fantasy genre while reviewing Game of Thrones, resulting in Patterson getting comments (before they were disabled and removed) ranging from angry fans bashing Patterson for "not getting it" to others expressing confusion as to why Patterson was reviewing the series when he clearly wasn't going to make any effort at being objective or give it a chance. Patterson was reportedly so rattled by the experience that he recused himself from reviewing the series any further.
- Mr. Welch never forgave Forgotten Realms for supplanting Mystara as the "default" Dungeons and Dragons setting, and rarely allows a mention of Realms to go by without taking a potshot (example: in a list of which film director would be the best fit for DnD's various settings, he dismissively saddles Realms with Uwe Boll).
- Discussed in his video "Game Critics". Dunkey notes that a critic's power lies in the consistency of their own opinions, so that a viewer can extrapolate an accurate judgment on a game based on what the critic says. He even points out some of his own steamrollers, such as Turn-Based Combat and Animesque games, but then points out that those biases should only make the viewer take a closer notice to when he gives a turn-based anime RPG like Persona 5 high praise.
- Dunkey has an extreme distaste for all non-Studio Ghibli anime, to the point where he'll often make assumptions about anime games he plays along the lines of All Anime Is Naughty Tentacles (such as in his Xenoblade Chronicles 2 video) and come into friction with those games' fanbases.
- He is quite outspoken about not liking JRPGs due to the anime influences they often, and thus tends to be overly critical of the genre when he does discuss them. This came to a head with his Octopath Traveler review, where he spent most of the video complaining about the genre, with only small parts of his video discussing the game itself. The community itself was not too thrilled at the video.
- Jo Cat makes no secret of his love of the Sword and Shield in his Crap Guides to Monster Hunter: World and Dungeons & Dragons, to the point of insulting and putting down other weapons/classes just as much as he advises on their proper use.
- MarioTehPlumber is a Troll, so naturally his "reviews" of Sonic the Hedgehog and Nintendo games on YouTube are absolutely full of bias. Most infamously, his extreme hatred of anything that he perceives to be even remotely sexual, even if it's not supposed to be (e.g. referring to Sonic's longer quills in his modern design from Sonic Adventure onwards as "Hentai quills" and accusing anybody who enjoys any Sonic game with the current design of "liking to shove his quills up their asses"). This bias takes priority over the gameplay itself in the "reviews", owing to MarioTehPlumber's "Character design > Gameplay" beliefs.
- James Lewell of Nitro Rad dislikes Jump Scares a lot in the horror genre, to the point where his reviews on The Crooked Man and Subway Midnight have segments breaking down why he thinks they suck.
- One reviewer for Wired magazine posted a Hogwarts Legacy review, giving it 1/10 stars. This would technically make it one of the worst video games ever reviewed by the magazine. The problem is that the "review" said almost nothing about the actual game, being instead a 1600-word rant against Harry Potter author J. K. Rowling due to her statements regarding transgender people... except Rowling herself was not directly involved in the development of the game. It was essentially emotional personal commentary rather than a legitimate game review.
- Parodied by The Onion's video review series with Peter Rosenthal, who plays a character for each review whose personal biases and experiences, some of which are very odd, are often allowed to completely dominate his opinion of a movie. For his review of Home Alone he's a gun fanatic who spends much of the review complaining about Kevin not shooting the burglars, he spends the The Hobbit: The Desolation of Smaug review comparing it unfavorably to a series of fantasy books he himself wrote, and gives a good review to Antichrist for its relatable depiction of the normal human stages of grief.
As I watched this film I found myself growing ever more incensed at the Ghostbusters for delaying God's retribution by storing ghosts in their Ecto-containment unit instead of sending the souls back to Perdition to suffer with all the other idolaters, fortune-tellers, and sodomites.
- The Mysterious Mr. Enter is another reviewer known for admitting he has a Bias Steamroller. Notoriously, one of the qualifications for a show being an "Animated Atrocity" is for it using Toilet Humor in excessive amounts, something considered "meh" by professional critics' standards.
- Nostalgia Critic-like fanfiction critic The Fic Critic (no, not The Fanfic Critic nor The FanFiction Critic) has noted that he tends to be biased against fics that act meanly towards certain characters or treats them badly, especially ones he likes. One noteworthy example was when he went from disdainful but amused at the stupidity of Web Of Shadows, a Spider-Man/X-Men Evolution crossover Parody Sue fic, to outright anger and chain swearing after Carlie Cooper called Mary Jane Watson, who he admitted is one of his favorite Spider-Man supporting characters, a slutty model who dresses like a street walker. His reaction to her calling Mary Jane this is one of the few times he went from snarky to outright pissed, and ended up giving that chapter a "Fuck/10".
- Feminist Frequency has a strong bias against violent media in all forms, and argued True Grit and Mad Max: Fury Road were anti-feminist because of their violence. More specifically, she has stated the belief that these movies do not fit her definition of feminism because they invoke masculine definitions of strength and conflict resolution.
- When it comes to fictional villains, film and animation reviewer Duckyworth loathes both Abusive Parents and the Enfant Terrible, and has repeatedly put characters that are either of those tropes (e.g. Ragyo Kiryuin and Cozy Glow) at the bottom of many of his "least favorite" character lists.
- Dead Meat: James revealed that I'll Always Know What You Did Last Summer is his most hated horror movie of all time, and justifiably so — it's so horrible that it scored an infamous 0% on Rotten Tomatoes. And when he finally does a Kill Count for it, he makes that fact perfectly clear. He sounds bored in his intro and opening narration, and instead of going into detail about the movie's production, he just says "this movie fucking sucks" before getting right to the recap. And before getting to the numbers, instead of doing anything from the movie, James smacks the film's DVD off his shelf and flips it off. James reiterates during the video's outro (and in earlier Last Summer videos as well) that I'll Always Know is his least-favorite horror movie of all time. He'd later call Mortal Kombat: Annihilation the worst film to be covered on the Kill Count, although it doesn't bother him as much.
- Much like Movieguide.com, Common Sense Media downright admits that it has a Bias Steamroller, not trying to pretend it doesn't have one. The organization reviews all sorts of media from a near-Moral Guardian viewpoint, and often rallies against violence in media. They have tried to tone down that aspect over the years and become more rational with their views, but occasionally it still pops up now and again.