Green’s Dictionary of Slang

(US) cheap muscatel wine.

1956		‘R. Macdonald’ Barbarous Coast 28: Lay off muscadoodle, lay off dames and reefers.
1963		A.S. Fleischman Venetian Blonde (2006) 231: Lock him and don’t buy any more of that muscadoodle. [Ibid.] 247: I smelled muscadoodle.
1989		Verbatim Winter 4: When he was on the skids...the favourite terms for...[muscatel] were muscadoodle and Napa Valley smoke [HDAS].
2004		J. Corwin A Grizzly Way to Die 6: They were fine, if all you wanted to grow were Tokays or sweet muscadoodle.