We only logged one so far that we actually didn't find. We read before we left that the cache was missing and we looked closely at the spoiler photos of where it should be. The spot was obvious so we took a micro out with us on our visit to some other caches in the area. We found the exact spot of the original cache and placed the micro there with a logbook (with our name in it as replacers, not finders). I only logged it because we had found the exact place of the original to put the new cache. The original CO has been inactive for a few months but should he ever get back to me I would be happy to change the log. I guess it's a bit like logging your own cache as a find except this was us trying to be helpful by replacing an inactive user's missing cache.