For anyone in a management role or a hiring manager in leadership, the question/comment below is one I use at the end of some of my most important interviews:

I'll say...."I'm just not sure you're ready for this role." 

Sit back and listen to how they respond. 

The ones unsure of themselves will fold. 
The winners fight back every time. 

I want to hire winners! 

 and when I'm still not sure if they are right, I see if my dog likes them or not.  :) 

 Haha great point!