I think part of the reason I prefer dust to mud, is the externalities. Generally, when it's muddy you can expect lower temperatures, more chance of there being rain in the air, and an overcast sky which makes everything look a bit drab and depressing. When it's dusty, so long as you're not actually in it (which just requires an extra 15 seconds of patience when the other guy takes off) the world is a beautiful place to behold, and one can ride with a t-shirt and not be cold (safe is another matter...) But, during the Spring months, this part of the world doesn't really have the capability to generate dust, even out in the desert.
Which reminds me when the soil is like clay, mud can be scary. This doesn't apply to Tillamook, I'm sure, but out in the desert you get a special kind of mud that builds up on your tires and never comes off, and I've heard stories of bikes with 10" of suspension travel get so much mud build-up on the tires that it rubs the fender constantly, eventually stopping the bike. We call it "Maupin Mud" and it's ridiculous.