This video by Chem-Dry of Richmond shows the in home oriental rug cleaning process by Chem-Dry. Chem-Dry of Tampa FL offers this same service along with offsite oriental rug cleaning for heavier soiled and stained rugs. Oriental rugs need to be cleaned carefully so they are not damaged by the cleaning process. Wool and silk rugs are made up of protein based fibers that run different risks compared to other natural fiber rugs. Although they don't have cellulose and are unlikely to brown they do suffer from color migration risks.
Color migration is when dyes on a rug migrate to other areas in the rug. This is common when wool rugs are cleaned with a solution that has a high pH or when the rug has been over wetted. It can be particularly noticeable when dyes migrate to the rug fringe, which is usually white cotton strands. In some cases dye migration can be corrected in most it cannot.
So how often should you have your oriental rugs cleaned? Your oriental rug cleanings don't have to be frequent but they do need to be cleaned. Cleaning frequency should depend on usage and and the type of rug it is. If it's in a high traffic area and gets a lot of use consider getting it cleaned annually. If your oriental rug is in an area of the house that is not used often then about every 1 -3 years.
Both wool and silk rugs will soil gradually and if they are showing soil on the surface then they are past due on a good cleaning. Don't let heavily soiled oriental rugs sneak up on you.