Fashion victim is a term - claimed to have been coined by Oscar de la Renta - that is used to identify a person who is unable to identify commonly recognized boundaries of style.
Fashion victims are victims because they are vulnerable to faddishness and materialism, two of the widely recognized excesses of fashion, and consequently are at the mercy of society's prejudices or of the commercial interest of the fashion industry, or of both. According to Versace, "When a woman alters her look too much from season to season, she becomes a fashion victim."
A fad is an intense but short-lived fashion trend. Fads are also by their nature at the extreme range of currently acceptable style, which means they commonly cross the line from the sublime to the ridiculous. Fashion victims can be seen to have crossed this line. (See Sarah Jessica Parker and Sex in the City.)