My rats only wear new clothes. They don't like dirt and keep away from mud. So the things they wear are clean (which means I didn't apply any weathering effects), so I just made a few layers of colours without washes, inks, etc.
But sure, weathering and dirt would fit to the skaven fluff. The only problem I wanted to avoid is, that bec. of the masses of fur and wood, these miniatures have brown as their main colour. I didn't want to increase the percentage of this colour when you look at the whole army. So I kept my fingers off washes and inks - bright colours look far better on the battlefield.
Greetings
Peter