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.
Alas, Poor Scrappy: After a roof collapses on her, Jessica Wallace (the resident highschool bully) only has moments to ask her boyfriend to tell her mother that she is sorry for being a disappointment before she dies from her injuries. The kicker: He had agreed to be her boyfriend just minutes before the accident occured.
Moody rich girl Serena Bishop suffered through attempted-rape, finding out her boyfriend was really her half-brother and a plane crash. She was eventually lost at sea.
Bridget Parker received much negative backlash from both the public and the media when she first joined the show, and many viewers called for her death. Ironically, just as fans had warmed up to her character, she was killed off in a freak car accident.
Ass Pull: The introduction of Jill Ramsay and her children in 2009, a Retcon in which Max Ramsay (a main character from the first year of the show) and Anne Robinson (who had been dead for years before the show started) were revealed to have had an affair, conceived a child (apparently some time after Scott but before Lucy) and given said child up for adoption. Since there's no way most of the Robinson or Ramsay family members who had appeared on the show could have been in the dark about it, one has to wonder how this story didn't come up when Max found out Danny wasn't his son in 1985, when Jim met his own illegitimate son Glen in 1990, or when Julie found out in 1993 that she was the result of Anne being raped by Jim's then boss. Reportedly the purpose of this was to reintroduce the Ramsay family to Ramsay Street, and apparently none of the age-appropriate existing Ramsays (Shane, Danny, Henry, Charlene or Gemma note though admittedly at least three of those would probably have required recasting) were interesting enough.
Brits Love Australian Soaps: To the point where viewing figures for Neighbours in the UK often surpassed the population of Australia. In fact, this is the only Australian series (and the last imported one to date) to have topped the ratings in Britain.
Ethnic Scrappy: The Lim family were introduced in an attempt at subverting Monochrome Cast, but thanks to their poor acting and out-of-character racist behaviour by other residents, their six week tenure is generally seen as an embarassment.
Not to mention his evil, murderous son, Robert Robinson.
Hilarious in Hindsight: Years before he became a major star on the show, Alan Fletcher guessed starred as a mechanic called Greg Cooper, talking to his current character's precursor Jim Robinson. Further, Cooper refers to his ex-girlfriend's new partner as "Karl".
Ho Yay: Ringo and Declan seemed, at times, suspiciously intimate with one another. They were even assumed to be a couple when they went on a weekend away.
Kelly Katsis initially mistook Toadie and Dan for partners
Libby and Steph had even greater levels of Les Yay.
Jerkass Woobie: Rhys Lawson. Despite the despicable things he did to get into the hospital's surgery program (namely, dating Erin just he could sabotage her and get her kicked out), it's hard not to feel sorry for him once he loses his dream due to a hand injury that he gained while saving someone's life after a car crash.
The Scrappy: As summarised here, Jo Hartman, Lisa Elliot, Eddie Buckingham, Nick and Caitlin Atkins, Lauren Carpenter (arguably Rescued in her 2013 return under a new actress), the Lim family, Katya Kinski, and to a lesser extent the Hancock and Parker families (Stuart and Ned excepted).
Kyle fell into this category around the time he moved into the street, seen by fans as annoying, dumb, pointless and adding nothing to the show whatsoever. His relationship with Jade did quite a bit to rescue him, however.
2002 is similarly unpopular, mostly due to Susan's losing thirty years of memory after slipping on spilt milk.
The 2008 season is fairly unpopular as well, due to a combination of unlikable guest stars, increasingly unlikable regulars, and popular guest stars who never got the chance to become regulars. The introduction of Lucas Fitzgerald and Donna Freedman (Margot Robbie) are seen as bright spots, though.
Take That, Scrappy!: Cody Willis calling Jo Hartman, "vacuous, inane and a waste of space" may have been intended as such.
Wangst: Zeke, for a while. Libby since her 2007 return.
The Woobie: Tash, she finds out her mother died because her dad was with another woman, the aunt she'd spent the last couple of months getting to know, then her dad leaves the country with the aunt leaving her to have to get a job to pay rent, then he sells the house, and she has to move in with a friend, who gets on her case for simple stuff like leaving dishes out.