At least these days they just mute the sound when they want to get rid of the swearing. I remember 20 or 30 years ago, when they would actually try to come up with another, more family-appropriate word, and dub it in with some other person's voice. So the voice didn't match, and the word didn't make any sense in context, and it was way worse (though sometimes unintentionally funny).
Still. If there's swearing in my movie, I want swearing in my movie. Censorship sucks.