Joan Crawford's final big screen appearance is in Trog, in which she plays an anthropologist studying a newly discovered troglodyte found living in a cave in the U.K.
One must, at first, adjust oneself to seeing a classic screen actress, such as Joan Crawford, in color, in a variety of colorful outfits, in a British film, spouting scientific jargon. After that, you can enjoy it for what it is: junk food for the brain. It lies somewhere between campy and good. The trog costume was notoriously "borrowed" from 2001: A Space Odyssey and doesn't try to hide it. The whole thing is played straight up, it's us the viewer who recognize the mockability factor now, years later.
I love Joan Crawford and feel badly that she was embarrassed by her last film, but maybe she'd be happy to know that audiences are still enjoying it all these years later.