Most people live two lives: A virtual one depicted by their online postings, and a real, day-to-day existence.

Now, in the wake of a court decision, employers may be advised to take a blind eye to derogatory — even profane — comments a current worker lodges against his company or boss in his virtual life.

At the same time, however, employers are increasingly scrutinizing candidates’ online personal activities in deciding whom to hire.

All this duality can be confusing, for both employers and ambitious workers intent on advancing their careers.

Due to a U.S. Court of Appeals decision to uphold a National Labor Relations Board ruling deeming online criticism of an employer to be protected discussion of labor issues, “employers should make sure that legal off-duty conduct is not used unfairly,” says Lester Rosen, CEO of Employment Screening Resources, Novato, California.

Still, because employers can learn a lot about a job candidate from his virtual persona that might not be uncovered in a physical interview, some 43 percent of hiring professionals reported using online screening in a recent survey from the Society for Human Resource Management.

If, when a hiring manager is conducting an online search, he uncovers a job applicant made “negative comments ... in a public forum about a past employer,” he should be careful not to use this “legal off-duty conduct” against the applicant, Rosen says.

But it would be easier for both individuals and employers, Rosen says, if workers close virtual doors on some of their discussions, using “some sort of private, password protected forum that is off limits to anyone not invited.”

Likewise, “if a person has made negative comments in a public forum about a past employer,” and that person is hoping to impress a future employer, it’s advisable to “put such comments behind privacy protection,” Rosen says.