I think it's not always accurate to judge someone's personality by their clothes. People often wear things for comfort or because it's easy, not always as a sign of their personality. For instance, someone might choose sporty clothes just because they are comfy, not because they are very sporty. It's good to keep in mind that there can be many reasons for choosing clothes, and they don't always show everything about a person.
私は、服装で誰かの性格を常に正確に判断することはできないと思います。人々は快適さや簡単さのために服を着ることが多く、必ずしも自分の性格の表れとしてではありません。例えば、誰かがスポーティーな服を選ぶのは、それが快適だからであり、必ずしもとてもスポーティーだからではありません。服を選ぶ理由はいくつかあり、人についてすべてを示すわけではないことを念頭に置くのは良いことです。