I've had it done - it was like an attachment from a steam carpet cleaner.
But a couple of weeks ago my cleaning lady (who came when I was out of town) told me that she had washed all of my cushion covers in the washing machine. I would have never thought to do that. They looked great.
I had a dog who was marking the material at the bottom of the couch. I took some hot soapy water and a brush and just scrubbed and scrubbed. Then I rinsed and rinsed and rinsed into a bowl with towels around to catch the overflow. It seemed to work pretty well as there is no stain or odor and the dog stopped doing it.