I’m looking for a book written in the 60s/70s…where the humans spontaneously combusting, and when the protagonist investigates, he finds out that they are actually being eaten, that’s is, their imperfections are the food of a particular alien species. I remember also that somehow while their imperfections are being eaten, they experience an orgasm? And then they come back as perfect Greek god people. This also happens to the protagonist because somehow someone figures out how to be ‘eaten’ by this alien. I remember the book cover had a drawing of these floating pool islands in the sky… Ring any bells?