Aunt Alexandra's arrival from Finch's Landing does include an aura of decadence around it. She had apparently arrived in her "bright green square Buick"--complete with her Negro chauffeur. She announces that she has come to live "for a while"--
"For a while" in Maycomb meant anything from three days to thirty years.
She has left her husband, Jimmy, behind at the Landing, and if one did not know better, it would appear that Alexandra had left him for good. Scout's description of her aunt is not exactly a wholesome one.
I guess it was her Sunday corset. She was not fat, but solid, and she chose protective garments that drew up her bosom to giddy heights, pinched in her waist, flared out her rear, and managed to suggest that Aunt Alexandra's was once an hour-glass figure. From any angle, it was formidable.
Alexandra hosted her Missionary Circle, with Calpurnia serving the all-white gathering. There is gossip galore, including talk of the Finches' "Incestuous Streak." There is a history of Maycomb County, including the story about a man named Sinkfield, who sold arms to the Creek Indians; and Sinkfield's Tavern, where Sinkfield bribed the government surveyors with liquor in order to receive a more favorable topographic adjustment for his property. Maycomb grew only slightly during the "War Between the States" and Reconstruction, providing few "outsiders" to enter Maycomb's strict "caste system." Alexandra's favorite Finch family gentleman, Cousin Joshua St. Clair, is introduced, but Alexandra's stories about him differ greatly from Atticus's.
"Why, Atticus said he went round the bend at the university. Said he tried to shoot the president. Said Cousin Joshua said he wasn't anything but a sewer-inspector... Atticus said it cost the family five hundred dollars to get him out of that one--"
Atticus tries to explain Alexandra's theory of "gentle breeding," to his children, but he thinks better of it when Scout begins crying. It's best, he tells Scout, not to remember Alexandra's history lesson and her ideas about heredity.
"I don't want you to remember it. Forget it."