For those social networking phenoms posting their every thought, drunken photo, tale of debauchery, and brush with the law on your MySpace, Facebook, and Twitter pages, a word of warning: You might want to tone yourself down if you’re looking for a job. There’s a 20 percent chance that your next employer is reading, judging and possibly rejecting your professional persona based on the private one you tout online. Based on a nationwide survey of more than 3,100 employers, CareerBuilder.com says 22 percent of employers are using social networking sites to research job candidates.