The laws of etiquette proclaim that we should not speak ill of the dead—especially the recently deceased. There is one place, however, where this offense is being committed with regularity: online obituary guestbooks.

Legacy.com is a company that provides online obituary services for more than 300 newspapers in the United States and processes more than 18,000 notes daily. Not all of those messages are glowing tributes. In fact, the company assigns 45 of its 75 employees—and spends 30 percent of its budget—to intercept messages they call "dissing the dead." Some of the barbs are unmistakable, such as off-color insults and scathing accusations. Many others are subtle, such as this one: "Reading the obituary, it sounds like he was a great father." This was signed, "His son Peter."

Kenneth J. Doka, a professor of gerontology (the study of aging), believes computer technology has made it easier for people to say something with one click than write a letter and put it in a mailbox.

"In more than 25 years of grief counseling," Doka says, "I can cite only a couple of instances of people communicating mean things to the family of someone who died by sending them a letter or writing in the paper guestbook. On the other hand, I've talked to a lot of funeral directors who have put up online guestbooks, and they say the level of screening required is a real problem."