I often create pictures of naked people, or drape my models in untailored flowing cloth. Its rather traditional for a couple of reasons. One is that flesh is beautiful and muscles and curves are the first thing to think about when depicting a human, even one who is then covered in fabric, to get the proportions right you must first visually dig down to the structure. Also flesh color is difficult and practicing it on the limbs makes it easier to work on the face. But the Main difference is deciding what to wear. When a subject is clothed the painting is no longer limited to the emotional timeless human experience, the painting gets aligned with history. The dress tells you what time period we're in and how much money the subject has, it indicates a lot about their personality, how warm it is out, how much wind there is, which country we're in. The anonymous human becomes a story, the look in their face and the pose still says everything human and emotional, but so much else is brought up when you add clothing.