how dirty can a k&n cone filter get before it becomes a problem? seems like i just cleaned it a few months ago, but it looks shitty already

 

You can clean them every 50k miles and you'll be fine. What you are seeing is perfectly normal, unless you live in the Sahara desert.

 

The outside air isn't as clean as you thought, this is a normal sign. Like DC2 said, just have it cleaned every 50k miles and you should be fine.

 

ive only had mine for about 10k and i cleaned it the other day it had all kinda dirt and shit on it. the whole filter was like a re clay color not dark red anymore. so i cleaned it and oiled it and it seems as though it doesnt struggle as bad when i drive with my ac on. and it seems as though it pulls better on the top end.