There are many ways to research the public records of a company. Go to the public or college library. They will be able to help you look for documents and trade journals. Criteria varies by industry but some include customer service availability, transaction systems security, and privacy and return policies. Hoover's Online gives company and industry information.
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There are many instances where the job description of the position doesn't match what you actually do after you accept. Sometimes this has to do with technology that they want to launch isn't on time, sales aren't happening as quickly as they thought, or they'll change your job duties. Ask to speak with people you'll be working with at your interview. Find out from them if the job they're doing is the one they signed on for. Ask if they're happy with what they're doing, their likes and dislikes about the company, and remember to ask for specific examples.