Inexperienced interviewers sometimes—out of nervousness or not wanting to hurt a candidate's feelings—make overly positive statements about the candidate's chances. That false belief can lead to suspicion (and legal trouble) when the person is later rejected. Some rookie managers also make on-the-spot offers, fearing the candidate will be snatched up.
"Even if you think someone is perfect for the job, don't hire him in the heat of the moment," says Ruth Haag, author of the Taming Your Inner Supervisor series. "Tell him you will call him in a few days so that you have time to think."