How best to clean silk/plastic flower arrangements?

shake off the dust outdoors, then use a silk flower cleaner available at craft stores

Use a blow dryer to blow off as much dust as possible. Use a damp toothbrush to remove the rest.

I just wash them w soap and water even if they r paper just don't soak

Take them outside and brush them off with a soft brush (I've used makeup brushes from the dollar store). I've also used canned air (the type you use on electronics).

You can wash plastic with dish soap. Then I would run a blow dryer over the silk stuff to get as much of the dust off it as possible, and then wash them too..... they may not be salvageable since you let them go for so long. This should be an annual job.

Oh my, that is a long time, 15 yrs. I clean mine when I do spring cleaning and fall cleaning by putting them under a gentle shower for 5 or 10 minutes. Amazing how clean they become. For that long collecting dirt, you may need to spray them with cleaner as well and keep rinsing until it all comes off.

The easiest way to clean dusty artificial floral arrangements is to set them out in the rain! If they're secured in a container, set the container inside a trash bag and cinch-up the bag ties around the base of the arrangement to prevent as much rain as possible from entering the container. If the vase/container is valuable be sure to secure it against wind, etc. I hv used this method for years and pass it along to all my clients and friends!!!

Use a blow dryer

I have heard to put them in a paper bag with salt and shake them. It's supposed to clean them. (I usually just spray them with a mild cleaner, hose them off and let them air dry.)

I would get rid of them after 15 years, they will cause allergies and breathing issues at this point. Buy new or buy real plants.