AS A TEENAGER in the heart of Illinois farmland, Christopher Justiniano would needle his friends, many of whom toiled on local farms, for wearing their dusty Carhartt pants and work shirts in town. “I would be, like, ‘Why are you wearing Carhartt all the time? That’s some farmer s**t,” said Mr. Justiniano. Back then, he saw cheap workwear as too utilitarian to don outside a barn. Today, Mr. Justiniano, 24, a Chicago-based national stylist for personalized shopping startup Trunk Club, has realized he was laboring under a delusion: “I’ve had this shift: That stuff is practical and I should be wearing it.” Even in the city,...