Car Cover, wash or shake?

I have a CA Car Cover plushweave cover for my 'bird. I have had it for my car since a bought it new back in '96. Now some 12 years later, should I think of washing it? Should I bring it to the cleaners? Is a shake good enough to maintain it?(which I do epriodically). It has never seen rain or the elements as my car has always been garaged, but I have noticed that after taking it off there is obvious dust trails on the paint surface/edges where the cover has been dragged. I make sure to never let the cover exterior touch the paint surface, but am concerned that with the NewEngland cruising season coming to an end, that the cover could be holding debris against the surface. Am I overthinking this?

Rinse with water and let dry.

i have had a calif car cover for many years, go to a commercial laundry and put it in washer and then in dryer with a bit of fabric softner on mid range heat they come out like brand new

rinse it or take to the cleaners. Does it have a tag on it showing or telling how it should be cleaned?