What do you mean by driveability problems with oil deposits on the Mass Air Flow sensor?

I have had numerous vehicles with K&N Air Filters/ FIPK and MAF and I have never had any driveability problems. In fact they have produced more power and some increased FE depending on the vehicle! My HCH is the first vehicle that I do not have at least a K&N filter because they don't make one for the '06 yet.Also, I have found that the K&N lasts longer in between washes, rather then having to replace. Meaning for example, with a paper air filter I might have to replace every 15,000 whereas with the K&N only 30,000 miles in between washes. I know there is a lot of hype out there for or against K&N filters or anyother type of performance products and the choice is yours. I just like to share the beneifts that I have recieved from continious use of a product.