I ask them a few questions and how dangerous they are when they do not get a sweet treat. That usually makes them a bit frightened and insecure. I comment on sloppy costumes and point out they must care better for coming across more convincingly. I also ask them if they will share what I give them or if it will be a fight or the sole possession of the one holding the bag - they usually get a bit irritated by this- some try to bribe me or act like little terrorists with threats. I do send those home to see their dad. When I like the critters I give each of them a little treat and mention that I am a witch and they must share their sweets.