More reasons to be careful about what you say at work

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If the Sony hack wasn't telling enough, there's more evidence that "confidential" is a laughable concept at the office.

A new CareerBuilder.com survey of more than 500 office support staff—including custodians, mailroom attendants, security guards, receptionists, administrative assistants and maintenance workers—found that 53 percent had overheard conversations about confidential topics such as planned layoffs, worker compensation or romantic relationships between coworkers. About one in 10 said they knew something about an executive or coworker that could be a firing offense.

Another 10 percent said they'd seen something incriminating in the trash or around the office. To highlight just a few: Stolen event tickets, a letter from the boss' mistress, an employee's tax return, a picture of a partially dressed coworker and a pregnancy test.

"Absolutely [support staff] are not out to get you," said Michael Erwin, senior career advisor at CareerBuilder. "They are stumbling across these conversations in the hallway, or finding that paper at the copier." The issue is more that busy employees can get careless, he said: Who hasn't printed something but then forgotten to grab it at the printer? Or had a water-cooler gripe session about the boss?

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Those missteps can quickly become problematic in the era of shared workspace. "There's no such thing as privacy at work," said Karen Friedman, a business communications coach. "Inquiring minds always want to know." The best defenses come down to exercising common sense. "If you have private information that you don't want other people to know, there are two things you need to do," she said. "One, zip it—just shut up, honestly." Don't talk about personal problems at work, and have sensitive work conversations with the office or conference room door closed.

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And the second thing? "Don't leave things lying around," said Friedman. Your desk is not a secure space. Just like you (hopefully) wouldn't leave your ATM card or a list of account passwords out in full view, don't think it's OK to leave sensitive documents or other personal items unsecured. Shred anything sensitive before it hits the trash or recycling bin.

Rethink whether some items should be going into the office trash at all, said networking expert Susan RoAne, the author of "How to Work a Room." (If you think you may be pregnant, take the test at home.)

Consider this a lesson, too, in office politicking. "The smart person in the workplace is as nice to the people in support roles as they are to everyone else," said RoAne. Not only can that make colleagues less inclined to gossip about you, it can also keep you in the loop on must-know information. For example, you might get a head's up about those planned layoffs, she said.