Mudslinging? Think again
Many people make the mistake of not leaving the woes of their last job with them when they look for new work. Many people have the tendency to rant to their interviewer about the problems they encountered in their last job, then suddenly segue into why they think the company they’re transferring to is going to be a much better one.

Having gripes about your past job is normal, but bringing it into a job interview is unprofessional. You may touch upon certain unpleasant aspects of your past job IF needed and only IF asked, but only lightly, and try to keep yourself as objective as possible. If your interviewer asks you about any mistakes you made, be straightforward in answering them and don;t forget to highlight what you did to solve those problems.