To make this even worse, a few of Kaiba's cards that were designed with the intent to make him look like an asshole have become Dracos in Leather Pant themselves. The Crush Card Virus is an excellent example, a horribly broken card that he used frequently, and while the OCG/TCG version was considerably nerfed, it was still incredibly broken. Nonetheless, no sooner was it available for TCG release than it became one of the most sought after cards in the game, and one of the biggest cases of Power Creep as players found ways to make it far more broken than it was. The card was outlawed eventually (many players say not soon enough) and players who objected to the ban never seemed to understand that when Kaiba first obtained this card, he was Bribing His Way To Victory, and shouldn't have been admired for it.
Yami Yugi has also been subject to the treatment in light of his Knight Templar tendencies. He becomes kinder over time, and some of his more ruthless deeds are absent in the Duel Monsters anime; but he's still ruthless early on in the manga.
Possibly a result of the leather outfit, badass dark powers, and backstory that has plenty of angst potential due to the death/entrapment/identity crisis triple threat.
Regular Marik isn't immune to this, either. He does have a sympathetic backstory, and he eventually goes through Defeat Means Friendship, but the fandom tends to ignore even the stuff that happened before aforementioned defeat, and claim that he'd be 100% good if not for Dark Marik. In the series proper, Marik, entirely without his Split Personality, had no problem with killing his own men or uninvolved innocents if it meant getting his revenge on Dark Yugi.
Valon has gotten this from fans who felt that he cared more about Mai than Joey did, just because he cancelled the duel between the two when the former was on the verge of losing, and believed that Joey cared more about dueling, even though in reality, he was the one who wanted to save Mai even if it meant her soul temporarily being lost, and that he originally intended to forfeit the duel to spare her. Guys, you can't do what you don't have the means to, and Valon specifically had what he needed to cancel the duel. Worse, they viewed Mai as an Ungrateful Bastard who Valon was too good for, even though he was partly responsible for her giving in to the Orichalcos in the first place, and was in a Yandere state. Granted, this was all under the effect of the seal, but still.
Jack Atlas went through a phase of Draco-dom when he was his bad self during the initial arc. Fans not only admired him for it, they encouraged it, and felt that Yusei and his friends were just weaklings, if not the ones at fault. The fans seemed to forget that Jack got to his current position by being a traitor, a thief, and almost a murderer. A case of Memetic Badass taken too far.
A more straightforward example would be Divine. He runs a school for Psychic Duelists just so he can raise them into an army he can use to take over the world based on the supposed prejudice he suffered. While appearing to the world as a Professor X-like figure, he also tortures all of the recruits to test their powers and kills them if they are not strong enough for him to use. This included Misty�s little brother Tobi which led to her death and rebirth as a Dark Signer. All the while he was manipulating Aki into being completely loyal to him while turning her into a monster and pretending to care for her. He also has multiple events that could easily be considered crossing the Moral Event Horizon such as torturing Rua in a duel, killing Carly by throwing her out of a skyscraper window when he caught her snooping around in his office and trying to drown Yusei and Mikage. He is the most purely evil character in the Yu-Gi-Oh! franchise that is not an Eldritch Abomination, insane, Made of Evil, or a several-thousand-year-old spirit of vengeance. However, fangirls like to ignore all of that and focus on his Mind Game Ship with Aki instead.
Kaito is an odd case. Fans often side with him over Yuma, claiming he's a better duelist with better cards, despite the fact that Kaito was a cold, uncaring Jerkass at times who was willing to take the souls of his opponents to meet his goals, which was morally wrong, however noble those goals may have been.
Shingo Sawatari. Despite the fact that his early methods are similar to the early manga version of Seto Kaiba, he is a Butt-Monkey in this series and is too funny to despise. Also, as an Expy of Jun Manjoume/Chazz Princeton. most fans predict that he's going to become a good guy anyway. Not to mention that his father seems to be a neglectful parent and is in fact a grade A Jerkass, cast some fan sympathy on him. His return in episode 49 cemented his turn to becoming a mostly decent guy.
Serena had some of this due to being the dimensional counterpart of Yuzu, and she is already claimed by some to be the best girl, despite the fact that she is a Jerkass who sealed Hokuto in a card, is every bit as bigoted against Xyz duelists as her colleagues from Academia, and is rude to Reiji and her bodyguard, Barrett. Fortunately, later episodes have shown that she isn't a complete jerkass and has been indoctrinated into thinking Academia was noble, not realizing that they were intentionally harming and hunting innocents in the Xyz Dimension invasion.
Shun Kurosaki. People admire him for his efforts to save his sister and comrades, sometimes completely forgetting how he ruthlessly turned at least FIVE absolutely innocent people into cards, not caring much if they also had family and friends whose lives he probably ruined. Also, he had no problems doing it to the LDS Trio, if Reiji hadn't intervened.
There's a significant swathe of the fandom that absolutely refuses to believe Dennis to be a bad guy, despite the fact that he works happily with the psychotic Yuri, he let Halil and Olga be carded without a care, and it's pretty clear that his prior niceness was a facade. He has shown some shades of Becoming the Mask in the form of concern for Gongenzaka, but whether it will stick has yet to be seen. Some of these have dropped their opinion since episode 74.
Well, Big BadZarc has an interesting case of this. At first, he was rather popular due to the intrigue that surrounded him due to being the Dragon Boy's original form and the cause of Yuya's Awaken ability. But when 136 came out and Zarc was revived to be a rather ugly dragon-human hybrid instead of his original form, plenty of fans hated him. But once episode 139 revealed his good looking human face, the same fans did a 180 turn and sympathized with him.
Revolver is meant to be a complex, morally grey character, like most of the characters in the show. While he is ultimately supposed to have a point on the dangers of the Ignis, he still commits many awful terrorist acts in order to achieve his goals, especially with the Tower of Hanoi, and openly admits to regretting having saved the Lost Incident kids as a child because of how it led to his father being put in a coma. However, because of his pretty looks, sympathetic backstory, and general coolness, many fans like to ignore or downplay his crimes, often excusing it by saying that he was only doing it for his father’s attention.
is an excellent example, a horribly broken card that he used frequently, and while the OCG/TCG version was considerably nerfed, it was still incredibly broken. Nonetheless, no sooner was it available for TCG release than it became one of the most sought after cards in the game, and one of the biggest cases of Power Creep as players found ways to make it far more broken than it was. The card was outlawed eventually (many players say not soon enough) and players who objected to the ban never seemed to understand that when Kaiba first obtained this card, he was Bribing His Way To Victory, and shouldn't have been admired for it.