Years ago I tried to put a couple of dry clean only bits in the machine machine because I wasn't happy to continue to pay dry cleaning prices (and couldn't really afford it). And, guess what? They came out just fine. I didn't put anything terribly delicate or 'structured' (like anything heavily pleated) but even a ladies suit jacket came out really well (it wasn't a natural fabric but I looked at it the other day and the fabric still looks good - the style of the jacket on the other hand...).
Have you ever washed an item of clothing marked as dry clean only, in the washing machine? If so, what happened?