Take note of whether or not they grin when they see you. Make an effort to be more present when interacting with people. If someone smiles and appears to be pleased to meet or speak with you, you most likely have a favorable influence on others and have good motives that coincide with it. Otherwise, you would not get a positive response. The truth is that we can never be sure about another person's intentions. All we can do is try to put ourselves in their shoes and decide for ourselves what we think they intend to do. If you find that you often have negative thoughts about other people, try to be patient with them and give them the opportunity to change.