Dr Karen (University of Queensland, Australia) Sullivan 
Mixed Metaphors [PDF ebook] 
Their Use and Abuse

Critics shudder at mixed metaphors like ”that wet blanket is a loose cannon”, but admire ”Life”s but a walking shadow, a poor player”, and all the metaphors packed into Macbeth”s ”Tomorrow, and tomorrow, and tomorrow” speech. How is it that metaphors are sometimes mixed so badly and other times put together so well?
In
Mixed Metaphors: Their Use and Abuse, Karen Sullivan employs findings from linguistics and cognitive science to explore how metaphors are combined and why they sometimes mix. Once we understand the ways that metaphoric ideas are put together, we can appreciate why metaphor combinations have such a wide range of effects.
Mixed Metaphors: Their Use and Abuse includes analyses of over a hundred metaphors from politicians, sportspeople, writers and other public figures, and identifies the characteristics that make these metaphors annoying, amusing or astounding.