Echo is often dusty. She just is. She and her mage help keep a storage room for many kinds of ingredients and supplies, but of course a wolf cannot climb the ladders to the taller shelves so she instead focuses on the sacks of petals and herbs and dried fungi that are kept on the lower levels. These sacks often spill or leak, and Echo is usually covered in at least one or two different ingredients.
On the rare occasion she is ever seen to admire herself in a mirror or still water, she seems quite happy with her speckled visage, often admiring how it adorns her cheeks or brow. The bright colours do look very striking against her glorious black fur, so perhaps Echo sees the decoration a little like we might see jewellery. Or perhaps she does not fuss, knowing that she is going to get covered in debris again no matter how much she shakes her coat clean. At the end of the day she is thoroughly brushed down and her coat freed of its gatherings, until the following morning when it will all begin again.