More and more employers are using social media outlets to screen their workers. According to online training company Mindflash, 45 percent of companies look at an employee’s profile on Facebook, LinkedIn or Twitter to make decisions about that person’s future in the company. An 11 percent of companies also look at personal blogs.

Most companies check when trying to make a decision on whether they should hire a person, but some companies continue monitoring social activities after that person has been hired. Experts are calling this practice “social media background checks.” Although technically employees should not be fired based on what they do on their free time, it’s hard to draw a line and expect companies not to cross it.

In fact, the National Labor Relations Board (NLRB) backed up employers in two Facebook-related cases in 2011. In both cases, the employees had made offensive comments about their job or bosses on their personal Facebook account and later received disciplinary actions because of those comments. When the employees complained to the NLRB, the organization declined to side with the workers.

A famous case involving Facebook includes a bartender from JT’s Porch Saloon & Eatery, which complained online about his job and his “redneck patrons.” Not only was he fired from his job for his remarks, but he was also fired via a private Facebook message, rather than by phone or in person. Another case involves Talk Radio Host Angel Clark, who woke up one day to find a message on his Facebook wall saying his weekend radio program had been cancelled because “we are moving in a different direction with our weekend programming.” Clark blogged about the situation, upset that he hadn’t even received a phone call about the issue.

Getting fired over Facebook is not a US-only phenomenon. A young employee in England was fired for posting on Facebook about his “incredibly boring job,” while Virgin Airlines fired a number of employees in 2009 because they complained that many passengers were “smelly and annoying.”

When Mindflesh asked employers what they were finding out from social profiles, they discovered that 35 percent of the findings were negative and only 18 percent were positive. Negative findings included inappropriate photos, bad-mouthing of their job and coworkers, and lies about qualifications. On the positive side, employers said Facebook was a good way to get a feel for the candidate’s personality, creativity and communication skills.

Probably the most worrying aspect of the whole thing is that Facebook has blurred the lines between “personal life” and “work” as two separate entities. It seems the only way to stay safe is to keep coworkers and bosses off your Facebook account. Mindflesh also recommends getting rid of your “digital dirt,” such as compromising photos and text you wouldn’t want your boss to find when Googling your name.

We cover this topic in detail in our Social Business College course.