Cult faves Gentle Giant--celebrated even today for their complex, sophisticated, eccentric recordings-- had to endure the most shaming indignity before heading out on the tour to support Octopus ( released in December of 1972). They had to open for Black Sabbath:
For the Gentle Giant novice, Octopus is the place to begin. It features all the odd, multi-instrumental, multi vocal adventures and twee and twiddly moments that are the hallmark of this band of brilliant musicians... with the benefit of being extremely listenable.
One of the album highlights is "Knots" which kicks off with three part a capella vocals and then just gets stranger and stranger.
I suppose the oddest footnote to Gentle Giant is the fact that upon the band's break up, Derek Shulman became a big deal at Polygram Records. He's the guy who signed Bon Jovi.