When I am out caching, if I find the cache and can open it, then I consider it a find, even if the log is too wet to sign. I keep a sharpie with me, so that way, even if the log is wet, I can sign the plastic bag, the cache itself or anything to show that I was actually there. I usually have an extra piece of paper with me too, so I can sign that and put it in the cache if needed.
If I find the cache, but it has been destroyed (I found one that was a birdhouse attached to a tree that was hit by lightning. The cache was literally blown up.), I will clean up the area the best I can, put what I can find of the cache back together and log it as a find. I will also log it as "Needs Maintenance" so the owner knows something should be done and other cachers will be aware.
If I see it, but can not get to it, then I don't consider it a find.