You do not clean a fur coat just because it gets dirty. The number one concern with fur material is that the natural oils in the pelts will dry out. If you feel a fur and then rub your fingers you should be able to feel a very slight oiliness. Dust, pollutants, and airborne particulates are attracted to this and get caught in the hairs of the fur. They then act as a sponge drawing the natural oils out of the pelts. These particles also have an abrasive effect on the hairs of the fur that can wear on the natural shine of the fur over time, causing it to look old and tired. When you clean a fur your primary goal is to remove these materials from the hairs. For this reason, when an expert furrier recommends cleaning your fur yearly, he/she is doing so in your best interest.