CHICAGO (MarketWatch) — The next time you apply for a job, don’t be surprised if you have to agree to a social-media background check. Many U.S. companies and recruiters are now looking at your Facebook, Twitter, Flickr and other accounts and blogs — even YouTube — to paint a clearer picture of who you are.

“Almost all employers do some form of background screening because they have to avoid negligent hiring,” said Max Drucker, chief executive of Social Intelligence, a consumer-reporting agency. “An employer has an obligation to make the best effort to protect their employees and customers when they hire.” Listen to audio: Your Facebook page is part of your resume.

And now the Federal Trade Commission has decided that companies that research how you spend your personal time and what your passions and hobbies are do not violate your privacy. The agency recently investigated Social Intelligence, which scours the Internet for the information, pictures and comments you freely share with the world and sells that data to your potential employers. The FTC found the company compliant with the Fair Credit Reporting Act. In other words, the Internet is fair game.

“When someone puts their public life out there publicly, it’s there to be evaluated,” said Kim Harmer, a partner at Harmer Associates, a Chicago-based recruiting firm. “You find out lots of things about people just by Googling them.”

It’s not the party photos

You can breathe a sigh of relief about those party pictures plastered all over your Facebook — most employers and consumer-reporting agencies will look past them, unless, of course, you’re underage.

“I look at their Facebook and see how they approach what they put on it,” Harmer said. “Is it immature? Appropriate or inappropriate? I’m not judging their activity but looking at how they communicate what they do and their thoughts and their judgments to the public as a reflection of what they will do with clients and team members.”

Drucker said he only searches for what the companies direct him to find and stays away from giving employers information that might be considered discriminatory to the hiring process. Employers, for example, cannot legally make hiring decisions based on race, religion, marital status or disability. But they can make decisions based on whether or not they like your attitude or your ethics.

A Social Intelligence report to a company would include racist remarks, sexually explicit photos or videos, or flagrant displays of weapons or illegal activity, Drucker said. And your decision to post a naked picture of yourself might not go over well with a potential employer.

“That might not be relevant to the job, but an employer gets to determine if that’s the kind of person he wants representing his company,” Drucker said.”We don’t make the decisions. We just generate the reports.”

He said he has been surprised by how many racist comments and flagrant displays of drug use people post online. “It’s not just smoking marijuana. It’s snorting cocaine, talking about doing Ecstasy on Twitter or a forum or message board, showing it in photos or video-sharing sites,” he said.

Some companies are mining photo- and video-gathering sites using facial-recognition software. If you were among those rioting in the streets of Vancouver after the National Hockey League championship, for example, a potential boss could find you the same way the police tracked down those responsible for some of the bedlam — in the pictures.

“We are going from the Web being a place of extraordinary anonymity to a place where your every movement could be traced if someone’s taking pictures of you and posting them,” said John Challenger, chief executive of Challenger, Gray & Christmas, an outplacement-consulting firm. “Job seekers need to be careful because of that,” so they don’t make a mistake and lose a job as a result, he said.

They also need to know that not all companies use reporting agencies like Social Intelligence. Some take a hodgepodge approach to mining your data.

“People are slowly becoming aware of the consequences of posting too much information on the Web,” Challenger said. “But they shouldn’t wait until they make a mistake and lose a job because of it.”

What you should do

Here are some tips: