A book-seller whose blog I follow has posted this:
A customer came to the shop and asked "Do you have the book "Rubble and Ashes"?
In German: "Schutt und Asche". This is a established term in German. In English that would mean something along the lines of "(reduce the city to) rubble and ashes"
So it's kind of understandable that she remembered the phrase, but not the actual title.
The book-seller was able to help out anyway, btw.
The whole point of me posting this is, that I always like to talk about "Diana anecdotes" (I'm a geek, did you notice?), and "A Breath of Snow and Ashes" is my favourite of the series.