If you've heard this story, please don't stop me. A major pet food company, after years of secret laboratory research by an expert crew of canine scientists, had actually formulated a new and manifestly better dog food.
To introduce its creation, the company recruited an all-star marketing, packaging and advertising team. The label for the can was colorful and creative. A catchy jingle was written, and within weeks, it was being hummed nearly everywhere. The clever TV commercials promoting the new dog food were positively received and even earned industry prizes.
But sales were worse than disappointing; they were dismal.
An emergency meeting was called at company headquarters to find out what mistakes had been made and to somehow escape the looming financial disaster. There was finger-pointing with the pet nutritionists, who hinted that the sales force had dropped the ball with the supermarkets.
There was widespread criticism of the advertising people for their failure to insert discount coupons in the Sunday newspapers. There were many excuses but no explanations. That is until, finally, the CEO's soft-spoken personal secretary dared to speak the unpleasant truth hiding in plain sight: "The dogs don't like the dog food."
That homely parable could be useful in trying to understand what has happened to some of the most promising presidential candidacies of the 2016 campaign.
Consider the case of former Florida Gov. Jeb Bush, who raised more than twice as much money as any of his Republican competitors — managing to scare 2012 nominee Mitt Romney away from a 2016 rerun — and widely outspent all his rivals in purchasing TV time to promote his candidacy.
He attracted a battle-tested and talented campaign staff and was endorsed by more Republican officeholders than anyone else.
But exposure has not been helpful. In June's Wall Street Journal/NBC News poll, some 75 percent of Republican voters said they could see themselves voting for Bush in the general election, but seven months later, in the most recent WSJ/NBC News survey, only 42 percent of GOP voters see themselves voting for Bush if he were to become the party's nominee.
By contrast, 67 percent of those same Republicans can see themselves voting for Bush's fellow Floridian Sen. Marco Rubio.
Democrats are growing increasingly nervous about the precipitous drop in voters' favorable feelings toward their party's consensus front-runner,
Hillary Clinton, from the time she left as secretary of state — when her personal ratings were 56 percent positive and just 25 percent negative — to today, when just 37 percent of voters view Clinton positively and 48 percent have negative feelings toward her.
Those numbers are identical to those in July's WSJ/NBC News poll despite the fact that in the past year, Clinton has raised more money and enlisted to her cause some of the most highly regarded young professionals from Barack Obama's winning campaigns.
She has campaigned ably and energetically, especially in Iowa and New Hampshire. But to voters hostile to the synthetic and hungry for the authentic, the rumpled, relentlessly unconvivial Sen. Bernie Sanders, who has never before run for office as a Democrat, has emerged as a serious threat to Clinton's inevitability.
Clinton, who has been a major American public figure for nearly a quarter-century — ever since her husband, the president, put her in charge of his eventually unsuccessful health care reform plan — is generally seen by voters as smart, as a strong leader and as deeply experienced.
But voters have serious doubts about her honesty and straightforwardness, and she has problems with personal likability.
Her public profile, in many respects, is not unlike that of one 1968 candidate who also had been on the national scene for two decades, Republican Richard M. Nixon, but he still managed to win two White House terms.
Mark Shields is a nationally syndicated columnist.