Green’s Dictionary of Slang

frivolous, banal, tacky; orig. and chiefly of pop music.

1969		N. Cohn Awopbop. (1970) 216: The way to break the bubblegum market is simply to shout, to be louder and flasher and more vulgar than the competition.
1972		Eble Campus Sl. Oct. 1: bubblegum – light, unimportant, frivolous, unimaginative.
1975		L. Bangs in Psychotic Reactions (1988) 170: Who else would [...] then redo his Hitler Youth blond so he resembled a bubblegum Kenneth Anger.
1977		C. McFadden Serial 24: If Harvey thought getting it on with some bubble-gum rocker was realizing his full human potential, well, that was his prerogative.
1999		Indep. Rev. 16 July 16: If you are trying to make it in the world of bubble-gum pop, then you are definitely next on their list.