A rule of thumb in journalism is that three of anything is a trend. Three losses by a sports team is a slump. Three mild winters is global warming. Three presidential affairs is … you get the idea. So what is three instances of journalistic malpractice?

CNN reporters now join Patricia Smith formerly of the Boston Globe and Stephen Glass formerly of The New Republic in the latest round of pretend reporting. Unlike Ms. Smith and Mr. Glass, the CNN crew stands accused less of fabricating people and events and more of trying to pass off questionable and scanty evidence as hard news.

Either through voluntary departures or firings, CNN cleaned house last week after the reporters and producers who assembled the shocking story of the government’s use of nerve gas during the Vietnam war were found to have leapt to conclusions that the evidence did not justify. After a review of their sources, the substance of the story took on the consistency of Jell-O on a July afternoon.

Ms. Smith, of course, left the Globe after it was discovered she made her columns more compelling by inventing characters who said just the right thing in just the right way. Mr. Glass was found to have in part made up 27 of 41 stories he wrote for The New Republic over the last three years. (Mike Gallagher, the Cincinnati Enquirer reporter who recently was dismissed because he may have illegally obtained the phone messages of Chiquita Brands executives, fits into the group under the rubric “ethically challenged,” but his sin was in going too far, rather than not far enough.)

Fellow journalists have offered the feeble defense of their industry by pointing out that, in every instance, the accused has been fired and publicly humbled. But that not only sidesteps the betrayal of trust with readers and viewers, it does nothing to describe how possible future scams might be stopped. That’s a true disservice, including for those in the business.

Here is journalism, a wonderful trade that done right, is difficult. It requires care and diligence. Done right, it is also exceedingly useful, giving readers an accurate view of events they could not otherwise see. Done right, its practice is both an honor and a good life.

All of that is threatened by the fiction writers in our midst.