When I adjusted the valves on the Concours I noticed there was a bit of oil in a couple of the spark plug wells. I was focused on the valve adjustment and didn't stop to research what might cause oil to blow into those wells. Now I know - and I'm going to end up taking the fairings, gas tank, etc off so I can remove the valve cover and replace the well seals and alignment dowels. Either those seals are worn, out of alignment because the dowels are missing, or it's possible whoever had the valve cover off before me didn't reinstall the seals or the dowel pins. I won't know for sure until I take it apart again. I'd read that you should make sure the dowels don't fall out when you pull the cover (which I did), but I didn't bother to make sure the dowels or seals were installed to begin with. I just assumed all the parts were in place when I started.
A couple of tablespoons of oil blowing into the spark plug wells on to the exterior of the plugs isn't that big a deal (it's been doing that for at least 1200 miles and maybe a lot longer) but as more oil blows in there it could eventually cause an electrical problem since the spark plug cables/connectors aren't designed to be immersed in oil.