Is your valve cover leaking? I just ask because a month ago, i thought my whole engine was leaking. There was oil on just about all parts, and it seemed like it was on every gasket. And the whole bottom of my car had an oil layer and splatters all over the place, you should've seen me when i changed my u-joints. It was filthy.
So, i had to fix up my valve gap anyway, so i did the valve cover gasket too. Two weeks later (its a daily driver), all the oil on the whole engine was gone. Maybe some residue or ooze here or there, but nothing that would make me change a gasket. And its all pretty much gone from the underside too.