I think it's the same way for both genders, people tend to associate with the smug, sarcastic, and funny characters. Typically "the *****" is the one who gets all the cool, or at least amusing, lines in an ensemble cast or team. That said, such characters while popular rarely do well on their own when they get spin offs and such as they really need a set of established personalities to play off of.
It's sort of like how Cartman is the face for "South Park" and Angelica tends to be the face for "Rugrats" both characters are complete jerks, but they tend to make you laugh which is why people like them.
Of course for some people this does backfire, for example Yahtzee and others of his ilk make a big deal about hating the whole Joss Whedon-schtick which is what a lot of these characters in heroic fantasy draw on, although he by no means invented it (Spider Man and The Human Torch were doing it before Buffy was ever conceived of).
It should also be noted that "*****" is not a negative way of spinning admirable traits, and when your dealing with a character like "Buttercup" the stuff you laugh at or that gets your attention are more character flaws that come out in amusing ways than anything positive.
That said it should also be noted that a "smug bastard" tends to mostly be appreciated by the group for which he represents. If your not American you tend to be annoyed by smug American action heroes for example, but less so by those of your own culture. Americans themselves tend to be the exception to this and more open minded. For example I've noticed a lot of brits and other Europeans echoing Yahtzee's sentiments when it comes to characters like "Nathan Drake" and so on, but Brits for example tend to be less judgemental of say James Bond (for whom it is also a character trait) or Aussies if they see an Australian character doing it, etc... But that goes increasingly out of context with this post.
Someone liking Buttercup "because she's a *****" is sort of like them liking Deadpool "because he's kind of an annoying jerk". In context it can be quite fun, and those two characters tend to stick out within their own universes because of how they behave. Also it helps that their worst character traits tend to mostly be unleashed on the bad guys, or in a way that's funny to an impartial observer (like a viewer/reader). If you were actually a Super Hero for example you would probably not be all that enthusiastic about working with Deadpool for all the reasons he's fun to read about. DC also has a cult classic of a character called "Ambush Bug" whose major feature is pretty much to be useless and annoying (but powerful enough in his own way you can't do anything about him, or stop him from showing up).
