Wow, something controversial at last!
There is a separate topic on “What is Your Criteria to Log a Find”, but this is cache specific so I will leave it here. According to the Groundspeak Rules, if you don’t find a cache it should be logged as a DNF, no alternative is suggested. In my opinion, if you replace a cache, with or without the CO permission, it is difficult to log a find on it, after all you’ve placed it, and you’ve done a good turn for the cache owner and the next visitor, but not for yourself. Twice my caches have been replaced without my prior knowledge and each time I have refused the finder’s Found log. Logging a FTF is even more diificult as it deprives the next legitimate finder of the FTF. In this case the cache had been visited the day before, so very unfortunate for those not finding, although reb10 clearly would not have found it and would have to have relied on the CO replacing it. Food for thought?