One of the aspects of Mark Twain's fiction is the way that he uses dialect to add a real sense of setting and place to his stories. The use of the dialect creates a much stronger sense of place and really helps to conjure up the setting of an ancient mining camp. Twain is very wise to make the decision he does of reporting the story as it was relayed to him. Note the following example:
Why, it never made no difference to him--he would bet on anything--the dangdest feller. Parson Walker's wife laid very sick once, for a good while, and it seemed as if they warn't going to save her...
Use of the vernacular in slang expressions such as "dangdest feller" and grammatically incorrect phrases such as "warn't" really help convey the setting that Simon Wheeler comes from and clearly not only conveys the humour of the story through the printed word but also demands to be read and heard.