There was a thread on this very recently.
I have roughly 12,500 miles on my car. Been running a VR intake for the last 4,000+ miles, and an AirRaid for a few thousand before that.
I have never re-oiled the Vararam filter b/c it has few miles on it, and I only drive the car in nice weather as well. I pulled out the MAF last week and it looked like the picture below. I'm not sure how it got that dirty, but it did. I cleaned it off with CNC MAF cleaner, but honestly haven't noticed much of a difference.