If the restaurant industry had its version of Brian Wilson’s “Smile” or Guns N’ Roses’ “Chinese Democracy,” it would be the mythical rollout of all-day breakfast service at McDonald’s more than 14,000 locations in the United States — supposedly in the works for years and the subject of endless speculation and buzz.

In the case of the Golden Arches, or for most other restaurants that deal with long-standing rumors about their menu or operations policies, the advisable public-relations move is to “let it ride” as long as the speculation is not malicious or false, said Derek Farley, president of Charlotte, N.C.-based public relations firm DFPR.

“My advice is somewhat counterintuitive to marketing,” said Farley, whose restaurant clients have included Applebee’s, T.G.I. Friday’s, Champps and Fox & Hound. “The best way to handle things like this from a PR perspective is let it ride. If you’re having a winning streak or pitching a perfect game, the last thing you do is start talking about it.”

McDonald’s chief Thompson only addressed the possibility of all-day breakfast when he took questions from Twitter users who sent live queries at the end of his interview with Carl Quintanilla on CNBC’s “Squawk on the Street.” His response did not differ materially from what McDonald’s has said about 24-hour breakfast before, namely that the company is open to it but has no immediate plans.

“Yes, we could consider it,” Thompson said. “We have to focus on our existing menu, but we have looked at breakfast across the day. We have it in some markets around the world.”

He noted that McDonald’s has all-day breakfast in some foreign markets and has explored “innovative ways” to roll that out elsewhere, adding, “I think we’ll be seeing some of those things in the near future.”

Farley said it was unlikely McDonald’s would move soon on all-day breakfast but added that Thompson likely commented on the question as a kind of low-risk trial balloon.

“Sometimes the best market research comes from all the feedback you get from one tweet or blog post,” Farley said. “It’s hard to believe McDonald’s talks to CNBC unless there’s a clear plan of attack. They may have dropped the hint of the possibility [of 24-hour breakfast] to see what kind of reaction they get.”