How do you know if someone is trustworthy?

Right away there is no way to tell if a person is trustworthy or not. You can meet a person and not know right away. You do know through your experiences with the person. As the days, weeks, and months go by, more is learned about the person that you are talking about. Then an accurate opinion can be formed. Has the person come across as honest? Or is there something about this person's behavior that sets off alarm bells in your head about their trustworthiness? I cannot say enough that an opinion can only be made though the experience with these people. If they have actions that earn your trust, then they can be considered trustworthy. After all trust is not given but earned.