It’s important to remember that most eager candidates are on their best behavior during an interview. They may give you the answers you want to hear in an attempt to make it obvious that they’re the right person for the job.

But there are ways to weed out the true prospects from the ones who don’t quite fit the bill.
Knowing what “red flags” to watch out for during the interview process can help save you the future costs of a bad hire.

• Unusually long pauses before answering certain questions.

• Inappropriate use of humor.
•  A sudden change in voice volume. 
• Overly complex responses to simple questions.
•  Blushing for no apparent reason. 
• Sudden significant changes in manner or pace.
•  Sudden loss of eye contact. 
• Non-verbal clues that convey different statements from the verbal statements.
•  Sudden heavy perspiring.

 
When any of these types of things occur, it may be appropriate to use follow up questions regarding the subject being discussed.  Similarly, red flags that appear on the resume should be investigated during the interview. All in all, it’s often more important to observe body language and non-verbal communication than what the candidate is saying.