• Information about alcohol or drug use (41% of managers said this was a top concern)

• Inappropriate photos or information posted on a candidate's page (40%)

• Poor communication skills (29%)

• Bad-mouthing of former employers or fellow employees (28%)

• Inaccurate qualifications (27%)

• Unprofessional screen names (22%)

• Notes showing links to criminal behavior (21%)

• Confidential information about past employers (19%)

• Be proactive. Use Facebook, LinkedIn, Twitter, Flickr, StumbleUpon, a personal blog, etc., to create positive content about yourself online. Ask to guest blog on reputable sites, or have others recommend you on professional Web sites. "These help you build an arsenal of good things about you," he says.

• Refrain from responding in kind. If someone trashes you, don't get in a tit-for-tat discussion. If someone makes false statements about you, immediately send them correct information or post it on your own blog or Web site. You can ask the person to remove the negative content, but they may ignore you. If an employer asks you about unflattering information about you online that is true, offer a brief explanation and then quickly move on to your positive attributes. "I think most managers do realize we live in a transparent world, and there are negative things in our lives," Beal says.

• Remember that Google never forgets. Put a Google alert on your name so that you are aware when anything is posted about you online. "This is where you're going to feel the most pain, because it's going to be easy for others to find what's being said about you, especially if it lands on the first three pages [of a Google search]," Beal says. "But the more positive stuff you have about yourself, and the more you keep it current, then the faster the negative stuff will fall off those top pages."