Wet or sketchy (covered in sand etc) descents aren't fun. I eased pretty hard on a misty rainy descent "just in case" in CA. However I also bombed down dry descents (even with bits and pieces of sand or running water). Since I rode up the climb first I had an idea of what to expect.

I absolutely love bombing down descents I don't know, esp those with hairpins or extra long curves (i.e. expect 180 degree switchback but it's closer to 220 degrees). I have some element of trust for the highway engineers and the speed limit signs, so if I see "Speed limit 5" on a bend, I know it's bad, but 25 means it's okay. I know the jokes about "if you fail civil engineering you can always work for the state" (told to me by a civil engineer working for the state). In foreign countries I wouldn't be so cavalier.

Descending is about trusting your bike, yourself, knowing the proper technique for looking ahead/cornering/braking, and learning how to ride "ahead" of yourself (looking up the road and assimilating what you need to do before you need to do it).

I found one thing that helps a lot - riding at night with a narrow spotlight type helmet light, preferably off road on narrow single track. Your world gets reduced to a 5 foot circle 15-20 feet in front of you. You literally cannot see closer or further away, or the sides. So your light (i.e. your head and therefore your eyes) follows the trail. You have to remember what you already saw, without looking again, and you have to think ahead as far as what you're about to see/assimilate. Do this a few times on flatter new trails going as fast as possible (meaning you go as fast as you think you can, then click it up a couple gears) - you want to reduce the time each bit of trail gets lit up, and to do that you want to go 15-20+ mph (up to say 30-35 mph on fast sections or descents). Suddenly all descents feel totally normal.

cdr