I remember Clooney saying somewhere that being in BATMAN AND ROBIN opened doors for him in Hollywood. By agreeing to be in that movie he proved he could be a movie star (and not simply a T.V. star that did movies).
Fandom kind of forces these actors to dump on those movies, because we want them to hate them as much as we do. But for an actor, what they might remember is how comfortable it was to work on the movie, what the food was like, the people they met. They're not responsible for the finished product, so as long as they have a good time while making the movie that's the important thing.
Conversely, some movies that we cherish as fans, where we want to hear how glorious it was to make the movie, could be films that bring back horrible memories for the actors--and they have to put on a happy face for the sake of the fans and suppress the trauma they experienced.