Mr. Raymond reveals that he is not really a drunk--he intentionally appears to be drunk so that people will leave him alone. As a white man who has a relationship and children with a black woman, Dolphus Raymond knows that he and his family would face unrelenting persecution if he simply defied Maycomb's "social" standards. Therefore, in order to live his life how he wants to live it, he pretends to be drunk. The residents of Maycomb fall for his sham by seeing him as the eccentric town drunk.
Dolphus Raymond is another one of Lee's logical, objective characters--one who does not fall prey to Maycomb's tradition of racism and prejudice. Besides Atticus, Heck Tate, Miss Maudie, and Link Deas are similar characters who are able to look past skin color to see someone's real character.
At the beginning of Chapter 20, Dolphus Raymond reveals his secret to Scout and Dill by giving Dill a sip from his paper sack. The children are surprised to learn that Dolphus actually drinks Coca-Cola. When Scout asks why Dolphus pretends to be an alcoholic, he explains to Scout that his actions help people latch onto a reason as to why he lives the way he does. Unlike the other white citizens of Maycomb, Dolphus openly associates with black people and even has several mixed children. His taboo behavior makes him an outcast in the prejudiced community. Dolphus admits that he's not being honest with people, but explains to Scout that his actions allow him to live the way he wants. Dolphus also tells Scout that she is too young to truly understand the community of Maycomb. Dolphus Raymond feigns alcoholism to avoid possible trouble with racist community members. Instead of seeing Dolphus as their enemy, they dismiss his behavior because they believe he is an alcoholic.
Mr Raymond just acts drunk so other people will leave him alone, this is because he is white but his wife is black. He is aware that because of the mentality in Maycomb, if he lets everyone know how things are the family would have been disgraced since it was a mix culture situation. The question of race comes up a lot in this book as it regards how others are viewed differently because their race and how this creates issues in the town.