What is an 'ambush interview'?

In an ambush interview the interviewer or reporter may use hidden cameras or one-way mirrors to catch the subject off-guard. In this way, they might catch the person in the act of committing a crime or saying something incriminating. Mike Wallace of 60 Minutes fame was often criticized for his ambush interview tactics. Some think the mode of interviewing is unfair and even underhanded. Others believe that it may be the best, and sometimes only way to find out the truth about a subject.