I never expected to tear up over a story about a mop. Tear up a time or two I did, though, while watching the film JOY, which tells the tale of a mop and the woman who became a multimillionaire following the success of her Miracle Mop creation.

Going into the screening of JOY, I didn't know it was about a mop. Nor did I know it was based on the real-life success story of Miracle Mop creator Joy Mangano of QVC fame. The trailer didn't reveal...