As is the case with many Flannery O'Connor stories, "A Good Man Is Hard to Find" offers the reader a very clear set of characters and a culminating episode of violence. The question of meaning for many of her stories, including this one, grows out of the attitudes and beliefs of the characters in the story.
In this story, the grandmother is the central figure. She believes that she knows best and that she has a good handle on the values of her society. She can glibly compare the society of her youth and the society she lives in now without complexity or doubt. She knows where the family should go on vacation. She is certain where the old house down the dirt road is also - until she realizes that she is not certain at all.
The grandmother's righteous certainty fails her and fails her family. Her mistakes lead to the death of her son and grandchildren. The cat which she snuck into the car causes the car crash and her insistence on visiting the house on the dirt road leads to the family's meeting with the Misfit.
Ironically, the one thing that the grandmother appears to have been right about is how dangerous her society really is. Instead of being helped in a time a need, she and her family are robbed and killed.
Yet she is only led to this proof of her views by dint of her own deceit (bringing the cat; causing the accident).
With these ideas in mind, we can say that "A Good Man Is Hard to Find" is suggestive of a consistency shared between a person, his or her views of the world and the episodes he or she will encounter.
Looking also at the restaurant owner, Red Sammy, we see a figure that views the past as a caring time yet treats his wife with complete disdain and lack of respect. He views the present, like his wife, with disrespect and so interacts with the world in this way, running a shoddy and un-patronized food stand.
The grandmother's impersonal and righteous view of the world is matched by that of the Misfit, who is arguably even more righteous and unyielding in his negative view of the society that has shaped him through punishment.
A lifetime of prejudicial attitudes is erased, however, at the end of the story when she realizes her helplessness and the fact that discriminatory views such as hers are related to monstrous behavior like the Mistfit's.