We witnessed a situation where the last cachers who found the first stage of a multi-cache posted in their note that they found the container at a position that did not correspond with the description of the cache. Therefore they MOVED the container to the position they recon was meant by the cache description.
This resulted in a situation where the next 2 cacher could not find the cache. When the owner investigated they could not find their own cache because it was moved by the cachers who did not ask their consent!
Always get permission from the cache owner before moving/replacing a cache.
The second cache that we found are still watched from time to time by us - numerous times people will log that they found the site but no container and then log a find. Been there however we know that there is a "dummy" cache location on the way to the cache location, which almost fooled us into believing that the cache had been muggled until we followed through to the actual co-ords and found the cache safe & sound.