Mary Jane Watson, who doesn't know about her? Successful model/actress, Spidey's girlfriend later turned wife...If you're into Spider-man you at least must know about Mary Jane and her overall presence in the Spidey universe.
Yet for some inexplicable reason, it seems that Mary Jane has gathered a lot of hate in the recent years (while Gwen Stacy, Spidey's doomed girlfriend, has been placed on a pedestal), whether it be from poor reinterpretations of her, annoyed fans, or writers who just don't get her character.
Why does she get so much unneeded hate? Is it because of an aspect of her character that nobody stands, or is it because fans are still butthurt that they killed off Gwen in order to make Pete/MJ canon?
First of all there must be a context. The core of MJ's character is that she is a fun, free-spirited girl who prefers to not take life too seriously, but at the same time she is a very supportive, loyal and good friend who'll help Peter (or her other loved ones) in any way that's possible.
Unfortunately, I think this aspect of MJ is lost on many writers, with many men claiming her to be a "slut" just because she doesn't take relationships seriously and therefore she's inferior to pure and innocent virginal Gwen (while ignoring canon facts that prove that Gwen wasn't as innocent as people thought; bedding Norman Osborn is certainly not a innocent act, ha!).
Other people downgrade other interesting aspects of MJ's personality and turn her into a watered down damsel in distress who's very clingy and emotionally manipulative, like MJ as she was portrayed in the old films and the 90s cartoon (she's unbearable in the 90s cartoon; dumping Harry after she accepted to marry him, and initially getting with Harry just to make Peter jealous).
It doesn't help that in later years writers are following pursuit and writing down a very unlikeable MJ in the comics to make Peter seem more vulnerable and justifiable in separating from her. (One More Day...). It's gotten even worse with the reveal of Spider-Gwen, with people proclaiming how "amazing" it is that the love interest is now an independent super heroine and she's a girlfriend for Peter because she can defend herself "unlike that useless Mary Jane".
So why do people hate her?
I think it's a combination of many different things rolled into one.
1- Gwen's death. People tend to be quite fond of Gwen so they were angry when she died because they felt the writers were trying to force down Pete and MJ together by killing off his current girlfriend. What no one likes to talk however is the fact that MJ and Gwen were friends in the original comics and her and Peter getting together was a natural progression of their characters, it's not like mary Jane came in and stole him from under Gwen's nose (something that's all too common in romance stories, and i'm afraid it's a cliche the new movies will do in the third film).
2-Her "sluttiness". People don't like the fact that Mary Jane was a bit of a flirt at times and didn't take relationships seriously, but this is actually a part of her backstory, due to her screwed relationship with her abusive father she has come to believe that relationships are always doomed. And then again, she grows out of this phase as the years pass on and turns into a more mature person.
3- The damsel in distress. People think she's just a useless girlfriend that does nothing but get captured and bring drama to Peter. Well at times she has gotten in danger, it's no different from any other character (Gwen Stacy and Aunt May were huge damsels in the comics, but nobody goes around hating on Aunt May and Gwen...), and even if that, she has taken up defense classes and training to protect herself in the comics once she knew Pete was Spidey. She's quite resourceful and always manages to find solutions for problems when Pete is unable to solve them.
Overall I don't think Mary Jane is a bad character, per se, it's just that she's been handled by writers who don't care about her or are very biased (towards Gwen or Felicia, or somebody else). i'm sure she can turn out into an amazing character if the right writer can get his hands on her.
Image by Nebezial on Deviantart.