When I am interviewing staff, the things I look for are very simple: can the person do the job, do they have the skills and experience needed to perform the duties of the job, and add value to the company. The second thing I look for is cultural fit: will the person fit in with the company and its current team.
As for the question about an interviewee being able to manipulate the interview in their favor, in a word - yes. A skilled interviewee who has done their homework, researched the job and the company extensively can manipulate a weak interviewer by taking control of the interview and steering it towards getting the job. This underscores the importance for companies to ensure that they train their managers in Interview Skills and have well-defined procedures in place for staff recruitment.
John in Oz