I agree that we sometimes should encourage people to watch their caches, and that caches that are not functioning, should be seen after, and eventually be archived.
However, in Denmark, a lot of caches are placed beyond immediate reach of the owner. I own a few of these. I travel the country perhaps 2 or 4 times a year, but not every week. If the logs indicate a problem with one of my caches, I disable it, and take care of it the next time I am around. My impression from fellow geocachers in DK is that this practice is considered OK.
I think many of us have searched a cache whose last successful find was one year ago, and perhaps with one non-finder in between. Sometimes we succeed, but more often we don't. The failed caches are among these ones. My strategy with these caches is to search them when I am around for other purposes, perhaps searching nearby caches which I am more confident of. This works very well. I waste little time, and report to the log so others can read that the problem (or my failure) persists. I admit that in a small and densely populated country like DK it is more easy to rely on such a strategy than in the Northern parts of the Nordic countries - and the Baltics - where geocachers may drive 200 km in vain for an unkept cache.
If we should pursue a "cleansing programme" for caches, I suggest that we concentrate on caches which have not been found for the last 6 or 12 months. In this way, we target caches which seem problematic, and we do not bother cache owners whose caches are OK.
The second subject of the thread is the physical standard of caches, that is, wet logbooks, missing lids, etc. It is obvious that serious geocachers report such missings, and that serious cache owners act accordingly within few weeks or months. I think very few cache-owners who do not respond to critical logs, would ever respond to a cache-purge.
All the best,
Dovregubben og Snöflingan (DogS), Denmark.