Green’s Dictionary of Slang

mickey adj.2

[abbr. Mickey Mouse adj.1 (1)]

(US) second-rate, corny.

[US]M.A. Crane ‘Miscellany’ in AS XXXIII:3 225: A mickey or Mickey Mouse band is not merely a ‘pop tune’ band [...] but the kind of pop band that sounds as if it is playing background for an animated cartoon.