"Wyatt Earp" was where I started to catch on, and the likes of "Waterworld" and "Message in a Bottle" have confirmed it. Kevin Costner considers himself God's gift to women, yet deep down, he has a frightening streak of sexism that affects all his work.
I lost track of how many times in "Wyatt Earp" Costner or someone else tells a woman to "shut up." Usually, the men are upset because those stupid, non-blood-relation women are complaining about having to move and/or be shot at all the time.
When the women aren't making unreasonable demands like that, they cling to him saying things like "I just want to be close to you." Translation: you don't have to marry me or even treat me well, just allow me to hang around and gaze at you adoringly.
Yet "Wyatt Earp" would still be bad without this sexism. It's too long, melodramatic in the extreme.