It wasn't me who pronounced the alleged "showboating" as unmusical...
Just because something doesn't float your boat doesn't make it "Unmusical", though the dictionary definition of unmusical is also deeply unhelpful:
1. not musical; deficient in melody, harmony, rhythm, or tone.
2. acoustically and aesthetically harsh on the ear; strident; dissonant; cacophonous.
3. not fond of or skilled in music.
According to my mother, a piano teacher, just about all rock and pop music is unmusical.
Many folks would find most free or improvisational jazz "acoustically and aesthetically harsh on the ear", but this fails to say which ear. If it's mine, that's not true. Many others would disagree, but that's taste - one man's beautiful music is another's nails on a blackboard.
So as a result I wouldn't say something I didn't like, whether it's showey-offey or just plain old Black Lace, was unmusical - but perhaps not to my taste. Or after a couple of beers, a steamy pile'o'sh!te...