I didn't clean it all out my first time and the car ran like complete shit for about 30 minutes. If you get oil in the cylinders you'll just have to burn it off. Not the end of the world, but a pain.
Easiest way i found was to get a normal 5/8 socket and dip it down in the galley as if you were going to take out the plug. Just rest it on the plug and pull the socket back out without turning it or anything. You will pull up a little bit of oil on the socket each time. Simply wipe off the socket and repeat.
Works perfectly and sure is easier than trying to aim a rag covered screwdriver down there.