Franklin uses a physical image to warn about the consequences of close association. Someone who lies down with flea-infested dogs should expect to pick up fleas; in the same way, spending substantial time with people whose conduct is harmful or dishonest can expose a person to similar problems. The effects may involve behaviour, reputation or involvement in difficulties created by others.

The proverb does not mean that people inevitably become identical to those around them, nor does it argue against helping someone who is struggling. Its emphasis is on influence and exposure. Close associations can affect habits, judgement and how others perceive a person, while the consequences of another person’s actions may also spread to those connected with them. Franklin’s broader lesson is that companionship should be chosen with awareness of the practical and moral risks that relationships can carry.