... to a geocache that you've put out? This is a discussion I've had with other cachers, and the answer I most often receive is a hand placed on the chin and eyes that look to the ceiling while the question is pondered.
The most obvious one for me is when a cache I've placed keeps getting vandalized, or stolen. If I have a cache that needs replacement 3 times in a short stretch of time (say.... 2 months), then it's time to pull the plug. Obviously, it's not a good spot to place a cache.
But, I'm sure there are other reasons. Let's hear what you're thinking....