El Greko's singing nightmare from Spain was called Baccarat, I believe. They seem to have been forgotten now, which is not a bad thing.
My own least favourite song of the seventies was probably "Daddy Cool" by Boney M. The ladies who had to sell this trash were joined onstage by a little wriggling man. He resembled a worm being toasted. This was the brainchild - or perhaps brain damage - of the German producer Frank Farian. He imported three competent West Indian lady singers and got them to chant a football crowd chorus, written in fake American slang, and recorded the ensuing abomination over an electronic drumbeat. It was moronic in a new sort of way - quite groundbreaking at the time. And what a horrible time it was. Inflation rose. Unemployment rose. Margeret Thatcher rose. Sales of nasty, brutish disco records rose. Not much nostalgia for those days!