Kroeger juxtaposes the Hull and Priest investigation (and “no-lie” investigations like it) with the work of aggressive journalistic liars because she finds unity in the two techniques, and wants to explore “whether there is really a difference for a journalist between not ever telling a lie—emphasis on the word telling, because lies, to qualify as lies, are verbalized—and the deliberate projection of a false impression with the clear intention to mislead, to deceive.”

But placing the Walter Reed investigation inside the same journalistic genus as the Mirage series constitutes a grievous taxonomical error. The “deliberate projection of a false impression” is something reporters do almost daily. When an official inadvertently spills the beans during an interview, the smart reporter suppresses his excitement and caps his pen in hopes that the official will dig himself in deeper. Such deliberate projections, by the way, must rank among the most common human activities. Parents scowl at their children to make them behave when they’re really not angry; buyers feign nonchalance to convince sellers to lower their prices; and so on.

In my mind, there is a world of difference between the two undercover genres. Compare, for example, the famous workplace investigations conducted by Tony Horwitz, Charlie LeDuff, and Barbara Ehrenreich, which Kroeger neatly summarizes, and the works of Silverstein, the Chicago Sun-Times, and¬†James O’Keefe and Hannah Giles, the contributors who pretended to be a pimp and prostitute in order to embarrass the advocacy group ACORN.

When Horwitz and LeDuff went to work at slaughterhouses for The Wall Street Journal and The New York Times, respectively, and Ehrenreich took menial jobs for her book about the working poor (Nickel and Dimed), the lies they told were de minimis. Ehrenreich, for example, omitted from job applications parts of her distinguished academic record. They created no new scenarios by their actions—they merely slipstreamed themselves into a story already in progress. Once there, they did little or nothing to contaminate the reportorial soil.

Silverstein, the Sun-Times, and O’Keefe, meanwhile, didn’t just contaminate the soil, they created it by telling their fictions. They then invited people from K Street, the Chicago bureaucracy, and ACORN to join the casts of their improvisation. The difference is between writing about a world that already exists, and conjuring one to embarrass the potentially guilty, a distinction Kroeger seems not to want to accept.

I would be misrepresenting Kroeger if I implied that she defends every lying reporter ever to carry out a convoluted sting. In her preface she writes that “at its best, undercover reporting achieves most of the things great journalism means to achieve. At its worst, but no worse than bad journalism in any form, it is not only an embarrassment but can be downright destructive.” I wish she were more judgmental about some of the techniques some reporters use, but Undercover Reporting is not that kind of book. If you are the type who seeks a thumbs-up or thumbs-down on every controversy, Kroeger is not writing for you.

You can sense her disapproval when she compares James O’Keefe’s ACORN sting with Ken Silverstein’s, but she doesn’t come out and say what I think she’s thinking: that O’Keefe is a crackpot and Silverstein is a genius. Instead, she writes, “What is most important in these cases is the exercise of sound journalistic judgment: to establish first if the deception was important enough to perpetrate, and after that, if accepted journalism standards have been fully adhered to and met, and if that can be reliably verified.”

If you’ve ever reported a story, you automatically understand the appeal of telling lies to get to the truth—they can be a wonderful shortcut! Conventional shoe-leather reporting requires time, sources, and energy, and must produce genuine findings in order to get published. But lie-based journalism works like EPO on both journalists and readers—it permits journalists to write bigger and faster (as if they’re writing a review of their own improv drama!), and the cat-and-mouse quality of the deception gives readers an extra, entertaining thrill. Not that giving readers a thrill is a bad thing, but I draw the line at turning news stories into episodes of Punk’d. Kroeger appreciates this, writing that even the well-intended sting can backfire and “veer off into the ridiculous or purely sensationalistic.”

Jack Shafer writes a column about the press and politics for Reuters.