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President Obama is nice to the “little people” – but his wife wishes he were tougher with his political enemies.

Ex-President Nixon was once observed sampling the dog treats he was feeding to his pet.

And Hillary Clinton is the most detested person to whom the United States Secret Service presently provides protection – so nasty to her agents that being assigned to guard her is considered, within the agents’ ranks, a form of punishment.

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Those are just a few of the juicy anecdotes to be savored in "The First Family Detail: Secret Service Agents Reveal the Hidden Lives of the Presidents" (Crown Forum Books, 2014), by award-winning reporter Ron Kessler.

Now heading into its second month on the New York Times bestseller list, the book is Kessler’s twentieth – his seventh bestseller – and it finds the onetime Washington Post colleague of Bob Woodward and Carl Bernstein in classic sleuth mode, ferreting out untold tales about presidents, first ladies, and their children dating back to the Camelot era.

In his recent visit to “The Foxhole,” Kessler told me his aim was to render the most accurate portraits available of these most prominent of Americans, to show “what they are really like as opposed to the image that they try to create, which is so often exactly the opposite of the truth.”

To accomplish that objective Kessler returned to familiar ground. This volume builds off of his 2009 book, "In the President's Secret Service: Behind the Scenes with Agents in the Line of Fire and the Presidents They Protect." For his latest book Kessler conducted interviews with more than 100 Secret Service agents, officers, and administrators.

Given that Secret Service personnel are, in fact, sworn to secrecy, Kessler acknowledged that those agents opening up to him, and providing the intimate details that enliven his books, are indeed betraying their codes of conduct and honor.

“I think they trust me to do an honest job,” he said by way of explaining the agents’ cooperation.

“I am genuinely interested in what they do, how they do it….They also feel that I already have many sources, so they might as well help out. And I really am the only journalist to be able to reveal what the Secret Service sees and how they operate.”

That window into the agents’ private world enabled Kessler to break the Secret Service prostitution scandal in 2012.

Kessler is no stranger to scoops; in a 2002 book, "Bureau: The Secret History of the FBI," the author pegged high-ranking FBI official Mark Felt as Woodward’s source for much of his “Deep Throat” reporting in Watergate, some three years before Felt acknowledged having played that role. (Kessler, in a rare encounter with inaccuracy, misspoke in our interview when he said he was best man at Woodward’s wedding; in fact, it was Woodward who had served as best man at Kessler’s wedding.)

But when it comes to the private lives of the presidents and their families – even when that personal conduct is so reckless as potentially to endanger the performance of official duties, as was the case for Presidents Kennedy and Clinton – does the public really have a right to know? Is the Republic well served by Ron Kessler when he publishes a book like "The First Family Detail"?

“It’s a very legitimate question,” Kessler replied, in his soft, almost whispery voice. He conceded that it is possible for a chief executive to behave badly in his or her personal life and yet still be a “good” president. But Kessler argued that he, as a reporter, is performing a valuable service to the electorate in delivering these intimate details about public figures. “When we’re choosing presidents, we should look at character overall.”