The viscose carpets and rugs are extremely popular at both ends of the market, cheap & expensive. They are so absorbent they accept all soils, most of which need water to remove them. The only safe way to adjust the soil is by using a dry compound process. It's better if you have a CRB machine to massage the granules but you could do a reasonable job with a stiff brush. Don't vacuum the granules until they are totally dry though. If you can remove the rug offsite all the better. If you have to use a pre-spray first make sure it's neutral and a really fine jet so you just mist it on. Good luck PP