yeah, that's on the to-do list, but it's only the outer surface of the outer filter that's dirty, the inside surface and inner filter are spotless (I do check before and after every run, I'm paranoid about killing the engine with dust)
p.s. filters should be oily (I use Putoline dirtbike sponge filter oil, which is dark blue, I spray it from the inside then massage it through the filter to get good coverage), dry filters are bad! Admittedly I went a bit overboard with the oil last time (hence the dark looking stain on the rear of the filter)