There's nothing like a spy story to get the journalistic juices flowing. They have all the elements. High stakes. Betrayal. And, if you're lucky, sexual intrigue.

The true import of spy stories is more difficult for readers to weigh. The facts are invariably spooned out by intelligence agencies whose interests lie mainly in covering up their secrets and obscuring their missteps. For understandable reasons, law enforcement officials seldom disclose exactly how they came to unmask the culprits. (If the National Security Agency were taping the cell phone calls of, say, Vladimir Putin, it would probably want to hide that fact.)

Over the past several weeks, readers have been treated to two very different spy stories. In both cases, some basic questions have gone unanswered.

I should say, there are few reporters in America whose careers have benefited more from spy cases then mine. As an eager, young member of the New York Times Washington bureau in 1985, I covered The Year of the Spy, which included John A. Walker Jr., who led a ring of Navy sailors spying for the Soviet Union; Larry Wu-Tai Chin, a Chinese-born spy within the Central Intelligence Agency; Jonathan Pollard, an American who spied for Israel; Edward Lee Howard, a dismissed CIA agent who offered his skills to Moscow; and Ronald Pelton, who betrayed a sensitive NSA program for tapping undersea cables near the Soviet Union. I moved on to cover myriad other topics, but I never lost my love for the spy/counterspy business.

Fast-forward to 2010 and the perplexing story of the suburban sleeper spies who were rounded up last month. Veteran spy watchers immediately noticed that not one of the 10 people charged with being Russian agents was actually accused of espionage. American laws are quite specific on what it takes to be prosecuted for participating in the world's second-oldest profession. You have to obtain "information relating to the national defense," which must be passed to a "foreign government" with the intent to harm the United States or help that power. The law, passed in 1917 as the United States entered World War I, mentions "codebooks, signalbooks, sketches, photographs, photographic negatives and blueprints."

When the Russian sleepers were charged with money laundering and failure to register as foreign agents (a law typically applied to miscreant lobbyists), it was evident that investigators had no evidence that real spying had taken place. Not once. Not in an entire decade of watching Russians come and go.

This raised an even more interesting question seldom raised on the spy beat: How much did the American government spend in following around this hapless band of sleeper agents? Surveillance of trained spies is no simple matter. Teams of specially trained FBI agents are needed to track a single suspect. Then there are wiretaps. American agents were likely keeping a close ear on the Russians' phone calls, if not their conversations. Transcribing and translating all that chatter soaks up enormous amounts of time and effort.

The cost here was certainly measurable in millions and millions of dollars. Don't expect the FBI to make a public statement anytime soon on how much was spent chasing Boris, Natasha and Anna. We've posed the question of cost to the bureau and will let you know should we get a reply.

If the national security value of these cases was minimal, they certainly were a boon for reporters covering them. Tabloids in New York and London could not get enough dirt on Anna Chapman, the sultry redhead (from a bottle) whose Facebook pictures were plastered across the front pages and on innumerable websites.

This opening sentence from the New York Post was a classic of the genre:

A ring of 11 Russian moles right out of a Cold War spy novel was smashed yesterday -- and among those busted was a flame-haired, 007-worthy beauty who flitted from high-profile parties to top-secret meetings around Manhattan.

Russian national Anna Chapman -- a 28-year-old divorcee with a masters in economics, an online real-estate business, a fancy Financial District apartment and a Victoria's Secret body -- had been passing information to a Russian government official every Wednesday since January, authorities charged.

This week, another spy case burst into public view. An Iranian nuclear scientist appeared at Pakistan's embassy in Washington telling a bizarre tale of abduction by U.S. and Saudi agents. Such stories are not entirely implausible. In recent years, there have been instances in which CIA officers snatched terror suspects from Milan and elsewhere.

This case, however, sounds like what is known in the spy business as a "clandestine exfiltration'' in which a person defects from one side to another and is spirited to a safe location. In the late 1980s, for example, the agency moved a Taiwanese nuclear scientist out of his homeland, a story I wrote about for The New York Times with my colleague Michael Gordon.

Today, The Washington Post's Greg Miller and Thomas Erdbrink published a scoop reporting that the Iranian scientist, Shahram Amiri, had been paid $5 million by the CIA for his secrets. One official said Amiri returned because he wanted to see his wife and 7-year-old son, who are still living in Iran and, according to The Wall Street Journal, had refused to join him in the West.

The disappearance of Amiri has specific echoes of the defection of Vitaly Yurchenko, the Soviet spy who fled to the West to join a girlfriend and then decided to return to Mother Russia.

There were theories that Yurchenko, the Russian who went home, was in a state of emotional crisis worsened by CIA handlers who did not understand his sensitive Slavic soul. Cynics questioned whether Yurchenko was a plant since the Russians allowed him to live freely after he returned. (My front-page story on Yurchenko's defection enraged him and prompted him to question whether the U.S. could keep secrets. I was among the handful of Western reporters who attended Yurchenko's "I'm headed home" press conference at the Russian embassy a few weeks later. Did he seem like he was acting? Who knows? It was a great story.)

In the coming months, American intelligence analysts will undoubtedly be intensely reviewing the Amiri case. Was his defection mishandled? Could the whole thing have been an Iranian ruse intended to either exaggerate or play down Iran's nuclear progress? It appears that Iran's seizure of three American hikers came just a few weeks after its nuclear scientist disappeared while on a pilgrimage to Saudi Arabia. Does that mean those two cases are connected?

But reporters should also be asking more fundamental questions. Is this sort of espionage in which nations try to recruit each other's citizens really worth all the bother? Even at the height of the Cold War, there were American officials who had their doubts. I recall a conversation in which the late Daniel Patrick Moynihan, once U.S. ambassador to India, observed that the information he learned from Indian newspapers was far more useful than what he could get from the highly classified analyses produced by American intelligence agencies. Moynihan, who was later a New York senator and vice chairman of the Senate Select Committee on Intelligence, understood the importance of a truly well-placed spy. But he was skeptical about whether the "take" from the more mundane spy operations justified their risks.

Don't expect answers anytime soon.

It's the spy business, Jake. [Here's that clip, along with some others.]

Update: Bill Carter, a spokesman for the FBI, sent an e-mail in which he noted that the investigation took place over a 10-year period and involved numerous field offices of the FBI. "We do not currently have a cost breakdown that we are able to provide," he wrote.