answer:I am not sure that this can be summarized as “society’s thought process” as much as it is how many people think and process first impressions. You ask a few different questions. This one …now I know someone who present themselves clean and collected is more likely to be trusted than someone who’s all over the place and dress dirty is easy, because a person who is careful to keep themselves appropriately clean and presentable and calm has enough presence of mind to make a thoughtful decision or to act rationally. The same thing happens for people who care for themselves in a healthy manner. It is not merely appearance, but an evaluation of how the person cares for themselves and thereby how they care for others. I work in San Francisco where there are many homeless people. Carl, the homeless vet who panhandles near the train, is always as clean and neat as possible, and friendly. William, who is often willing to open a door to the local coffee place, is alternatively presentable and polite, or covered in filth and nasty. While William gets my prayers and sympathy, he is not someone I would rely upon as I would with Carl.