The Collaborative International Dictionary of English v.0.48:

Flashiness \Flash"i*ness\, n.
   The quality of being flashy.
   [1913 Webster]

WordNet (r) 3.0 (2006):

flashiness
    n 1: tasteless showiness [syn: flashiness, garishness,
         gaudiness, loudness, brashness, meretriciousness,
         tawdriness, glitz]