Roger Waters did not sing "have a cigar".
From "Echoes: The stories behind every Pink Floyd song" by Cliff Jones.
"The vocal on the track is taken, for the first and only time, by someone outside the Floyd. Waters's struggles to get to grips with the vocal on 'Shine On You Crazy Diamond' had left his voice severly stressed and overworked. Gilmour didn't feel he could do the song justice....Roy Harper, the Floyd's Harvest labelmate, was recording in Studio 3...and Waters decided that the uncompromising singer - who had inspired the Floyd to produce 'Echoes' - would be perfect for a song about the evils of the music business. Despite the end result being one of the best vocals on the album, Waters now feels that he should have done it himself..."
AND...just listen to the vocals. Roy's voice does not sound one bit like Roger Waters' voice.
Electric Guitars are the inspiration for cries of "Turn that damn thing down"-Gibson website