The conversation that the Misfit has with the grandmother reveals what a disturbing and chilling individual he is. His phrase that he repeats most acknowledges this through revealing a particularly twisted psyche that only finds enjoyment in life out of doing bad things: "No pleasure but meanness." Note the following piece of information the Misfit tells the grandmother and what it reveals about him:
I found out the crime don't matter. You can do one thing or you can do another, kill a man or take a tire off his car, because sooner or later you're going to forget what it was you done and just be punished for it.
The Misfit reveals he is a man without any moral code whatsoever except a commitment to "meanness" that means he can engage in whatever criminal activity he desires without fear of any consequences except for some form of punishment exerted by the state. Perhaps what is most chilling is his belief that whatever you do, you will forget about it eventually, whether it is a minor infraction or something much more serious. This of course makes the grandmother's claim that he is a "good" man all the more ironic.