Well, actually there are two keys incidents in the HPverse where the Trio are led to make that mistake - the Quirrell/Snape stuff in PS, where Snape's hostility to Harry makes him effectively the only suspect, and the Moody ferret-juggling incident, which makes the Trio (well, Harry and Ron, anyway) utterly convinced of Moody's bona fides and general all round Jolly Good Egg-ness. And the plot of Pride and Prejudice depends on Darcy being snobbish about Elizabeth, and Elizabeth disliking Darcy.
But I did mean "bad" as in "morally suspect" rather than "likeable". Once again, I go back to Honor Harrington for examples. Honor in the first book is widely disliked by her crew because they think she's responsible for them having been handed the hiding of a lifetime in some wargames. In fact, it's because the wrong-headed materiel theories of a pigheaded admiral has gutted her armament. The pigheaded admiral hates and resents her because she thinks Honor should have done better with materiel given, and so sends her off to a dead-end posting. She's dumped in an impossible situation at the dead-end posting by a cowardly and inept superior officer who resents her for having broken his nose and several ribs when he tried to rape her at military school. In the course of the first book she has to win back the crew's respect (and those whose respect she doesn't win are unquestionably presented as bad - they only don't respect her because she reveals their laziness, cowardliness or ineptitude), demonstrate her superior moral integrity (making an enemy of the industrialist Klaus Hauptmann, whose ships she intercepts smuggling furs on the protected species list, and whose respect she wins in a subsequent book by her self-sacrificing defence of his ship), win a battle against tremendous odds despite the duff armament, protects a planet from invasion and ends up with promotion, the personal thanks of the queen, and a chance to tell the pigheaded admiral face to face how she got the armaments wrong. Oh, and she agonises with guilt for days over the deaths caused in her defence of the system against impossible odds, comfortedd only by her empathic alien tree cat, to whom she is psychologically bonded.
no subject
But I did mean "bad" as in "morally suspect" rather than "likeable". Once again, I go back to Honor Harrington for examples. Honor in the first book is widely disliked by her crew because they think she's responsible for them having been handed the hiding of a lifetime in some wargames. In fact, it's because the wrong-headed materiel theories of a pigheaded admiral has gutted her armament. The pigheaded admiral hates and resents her because she thinks Honor should have done better with materiel given, and so sends her off to a dead-end posting. She's dumped in an impossible situation at the dead-end posting by a cowardly and inept superior officer who resents her for having broken his nose and several ribs when he tried to rape her at military school. In the course of the first book she has to win back the crew's respect (and those whose respect she doesn't win are unquestionably presented as bad - they only don't respect her because she reveals their laziness, cowardliness or ineptitude), demonstrate her superior moral integrity (making an enemy of the industrialist Klaus Hauptmann, whose ships she intercepts smuggling furs on the protected species list, and whose respect she wins in a subsequent book by her self-sacrificing defence of his ship), win a battle against tremendous odds despite the duff armament, protects a planet from invasion and ends up with promotion, the personal thanks of the queen, and a chance to tell the pigheaded admiral face to face how she got the armaments wrong. Oh, and she agonises with guilt for days over the deaths caused in her defence of the system against impossible odds, comfortedd only by her empathic alien tree cat, to whom she is psychologically bonded.