【Gaudy】 , 【tawdry】 , 【garish】 , 【flashy】 , 【meretricious】 are comparable when meaning vulgar or cheap in its showiness.
Something is 【gaudy】 which uses gay colors and conspicuous ornaments or ornamentation lavishly, ostentatiously, and tastelessly.
Something is 【tawdry】 which is not only 【gaudy】 but cheap and sleazy.
Something is 【garish】 which is distressingly or offensively bright.
Something is 【flashy】 which dazzles for a moment but then reveals itself as shallow or vulgar display.
Something is 【meretricious】 which allures by false or deceitful show (as of worth, value, or brilliancy).