I have thought about this for about a year but in these past few months, it's heavy on my mind. One thing I've noticed about deceived people act is that they will support what you say and do even if you are exposing them. Now, there is a point when they will come out of their shell and speak out (more in a sarcastic manner). We'll use Judas Iscariot is the base for this post.
If you were to look through the 4 gospels, Judas Iscariot is fairly silent around Jesus. But around the chief priest, he's talking & talking. Sounds like people in church who just like to talk and talk (they have a form of worship, but no effectiveness). Anyway, in Luke 22, right before Judas went to the chief priest, Satan entered Judas. So now Judas was in the right company to be who he really was, a deceiver. He was able to talk and not feel tormented. When Jesus declared (in Matthew 26) woe unto that man by whom the Son of Man is betrayed. Judas responds like this: Master, is it I? Kinda like, I know you're talking about me, but I wonder if you're going to let my real character out. Yep, Judas was very defensive & tormented. When you call that spirit out, people will become very defensive because their dirty laundry will be exposed. In John 13, when Jesus got in Judas' personal space, He told him to do what he intends to do quickly.
John 12 shows one more side of deception. When Judas questioned Jesus about the ointment not being sold, Judas had an ulterior motive, to take the money for himself. Deceived people are easy to spot because they have an ulterior motive for evil purposes and/or selfish purposes. If their talk is about them, only them and what people need to do for them, what God needs to do for them, there's a strong chance they are deceived. Some will go as far as to throw in some religious lingo to try to look innocent.
But keep in mind, people being deceived will keep the mask over their face, look innocent, smile in your face until you get close to them and confront. Then deception and his cousins will come out from within. Once you start exposing things in a person's life, they'll initially remain quiet like Judas and stand with you until you increase the intensity of the exposing.
So this is how deceived people act.
The Mayne Man