The Ugly
It is not a certainty that anything was wrong with the clothes John was wearing or the way he was dressed, but that possibility certainly exists. Consider that the clothes a students might wear to school are often more casual than what would make the best impression on a prospective employer. In addition, if John was taking physical education, his clothes might be wrinkled from being in a locker while he was "dressed out." The possibility even exists that there would be an olfactory problem (good vocabulary word if it's unfamiliar).
In general, it is usually better to bathe and dress especially for the purpose of going to talk to somone about a new job. The old saying about first impressions being very important is very true.