I've ran K&N and S&B filters for years and I have never had oil coating issues with my MAF or TB. Even so, I have some MAF cleaner and I tend to clean all my MAFs every few months or so, they are always clean, never get much if any dirt.

I agree with Farnsworth, I think people over oil there filters a bit too much. IIRC in the instructions it says to LIGHTLY oil the filter, let it set for a bit, and hit any areas you might of missed....