It probably hadn't been cleaned since the house was built some fifty years ago. It turned out so nice that I cleaned two others. Each took close to half an hour, but they are now spotless. There are six more vents in the house, so I'll probably end up doing those as well. The ductwork still needs cleaning, but that will require professional help. I'll be disappointed if the professionals don't comment on the tidy vents.
Though I might be getting a bit obsessive about cleaning the house, there is a timely reminder of how fastidiousness can go too far. Observe W's bizarre behavior after shaking hands with a Haitian. This was weird even from a guy with a history of being weird. (The video might take a while to load. It's getting a lot of traffic. Everybody on the Internets will probably link to it by Friday.)
A scheduling conflict will most likely lead to the postponement of tomorrow's head yanking. I hope I don't have to wait another entire week. I had another unintended nap on the couch this evening and it left my neck feeling very sore. I need a longer couch. Or shorter legs.