That is what Dan Klein and I used to call it. Now there is some research, by Omri Gillath, Angela J. Bahns, Fiona Ge, and Christian S. Crandall:
Surprisingly minimal appearance cues lead perceivers to accurately judge others’ personality, status, or politics. We investigated people’s precision in judging characteristics of an unknown person, based solely on the shoes he or she wears most often. Participants provided photographs of their shoes, and during a separate session completed self-report measures. Coders rated the shoes on various dimensions, and these ratings were found to correlate with the owners’ personal characteristics. A new group of participants accurately judged the age, gender, income, and attachment anxiety of shoe owners based solely on the pictures. Shoes can indeed be used to evaluate others, at least in some domains.