I agree with Post #2, the Master was continually suspicious of the dwarves, secretly believing them to be "frauds who would soner or later be discovered and turned out" (180). The Master does not really believe Thorin until the company actually leaves to make their way up the Lonely Mountain. At this point, the Master is glad to see them go and hopeful that their success will equate a handsome reward for the men at Lake-town who helped them.
He never believed Thorin. He was suspicious from the start, but he pretended to believe him because the people in Lake-town seemed to enjoy their company. He basically let his people make the decision of whether to let them stay or make them go.