I don't agree TB about Tom knowing that Carlo was a gold-digger. Carlo is, in effect, marrying into a royal family. But, there's nothing to indicate that Carlo's future will involve infidelity, domestic violence, and eventually betrayal. As the novel points out, his use of a gun when he was younger was an indescetion that Vito and Tom were aware of. Given that he was Italian and half-Sicilian, came to the family through Sonny, and certainly knew who the Corleones were, there is some basis to believe that his employment in the family business was possible. Obviously, Vito's insight led him to be cautious with Carlo.