Lee Kaufman and her husband, Morty, were unlikely celebrities when they agreed in 2014 to appear in commercials for the Swiffer line of cleaning products. She was then 91 years old. They were the pioneers in an advertising strategy built on ordinary people, rather than actors. The public responded with adoration and an Internet click count that soared into the millions.

They appeared on TV shows and news outlets. The cleaning products weren’t the attraction; what generated fans was that the Kaufmans had a finish-each-other’s-sentences cuteness about them, and they seemed to have mastered the secret to a long and happy marriage, The New York Times said.

Mrs. Kaufman died on Dec. 18 at a hospice center in Port Jefferson, NY. She was 99.

In 2013, Mrs. Kaufman told Newsday that her late-life fame held a lesson. “The bottom line is, don’t die young,” she said. “There are too many things that can happen.”