I never listen to an audiobook for a book that I haven't previously read.
And I never accept the idea of someone saying they've 'read' a book when all they've done is listen to the audiobook. Two totally different processes. Reading requires the use of abstract thought process that begin with assembling letters into words into sentences into paragraphs into chapters, understanding their literal meaning, and then having an emotional or intellectual reaction.
Audiobook listening skips all the abstract bits and goes straight to the reaction part.
That said, I do enjoy listening to certain audiobooks (particularly the better DW books) when I'm exercising or when I'm on a long car trip. Having read the book first makes the experience far more enjoyable, especially great when a great reader (like Stephen Briggs) voices the characters in ways that make the words you read come alive.