I assume you are talking about the oil/grease on left side of engine. That is near the oil cap and depending on who changes it, it will drip down. Notice the right side is spotless. Hope that helps but a sure sign is milky oil on dipstip.
Doesn't look at all like a head gasket problem. Instead it appears that someone perhaps whoever changed the oil either spilled some onto the valve cover or put the oil filler cap on the valve cover by the oil fill hole with the cap upright so that some drained off the bottom (downside) part of the cap onto the valve cover. Suggest cleaning the area to avoid dust collecting on the oil and also checking to see whether the oil reappears, which seems unlikely.