I've seen quite a few stills for McLintock on the web, more than any other movie. There are some that look like vidcaps from the actual movie and others that are obviously posed. I think the studio must've wanted some good clear otk shots to use for their posters and newspaper ads that didn't have the motion blur that the frames from the film would've had. In one color still, you can see that Maureen O'Hara isn't wearing exactly the same outfit that she wore in the movie, because her corset has purple trim instead of green.