Green’s Dictionary of Slang

(US campus) something out of style or fashion; thus polyester princess n., a woman who dresses in out-of-date fashions.

1990		Eble Campus Sl. Apr.
1996		Eble Sl. and Sociability 42: Alliteration marks [...] polyester princess ‘female who dresses out of fashion’. [Ibid.] 60: Polyester, once the miracle fabric for the non-wrinkled look, has [...] come to stand for ‘something out-of-style or fake’.