What air filter are you running.

whatever what crap. thats all i ride in s dusty areas. i have the outerwears pre filter on the filter and the outerwears air box lid. that really keeps it nice.

when i clean my filter is is always clean. i clean it about once every 2 rides depending on how long and dirty it is where i am riding.

make sure you oil it all right as well.
 
a good thing to test your air filters is to apply a light coat of oil in your intake tract.
go riding, come back, check out your intake tract.
is there obvious dust?
or is it clean?
personally, i do not like k&n because they did not do well on this test, the filter was clean and oiled.
uni did not do good either.
i was happiest with notoil, twin air, and the oem filter on my bike.
 
I like my UNI I've Never done the test described above but I noticed the K&N was passing to much dust when I rebuilt My motor and I had red clay dust burnt to the top of the piston, also I seperate the 2 halves of the uni when I clean it and Ive noticed that the inner half stays pretty clean compared to my K&N which was dirty all the way through
 
buddy before me with the 240 cylinder either ran a non oiled K&N or no filter at all. my shop said it was the worst they've seen. we BARELY saved it. and even at that, it still really needs a re-sleeve.
 
I run a K&N and it stays clean because Im up front always..LOL. Really it is about maintenance. Clean your stuff and it will be just fine. You could run any filter into mud or water and it still could suck stuff in.