oil on spark plug?

[Dr3w2k5]

so during my endeavor of replacing plugs and wires, i found out the the left rear plug (cylinder 4 i think) is covered with oil. the oil was not on the node, but from the threads up to where the sockets attaches (the name has slipped my mind). im posting pics in a bit, waiting for camera to charge. Any ideas? bad valve cover gasket?

[wadespencer99]

Yes, most likely one of the spark plug 0 ring gaskets are leaking.

[brapple]

agreed, if the threads and up have oil on it then the o-ring in the vavle cover is leaking.