As a 17-year-old unsupervised male cacher (no worries, a few months and I'll be legal), lemme give a promise to you that the caches I inevitably hide are all going to be in sealed containers, with actual good information, surrounding terrain, parking, clean logsheets, no thorns, and significantly less fecal matter than all of these posts talk about experiencing. I apologize on behalf of my kind.
The worst cache for me was actually at absolutely no fault of the CO, however, it was a pretty unfortunate circumstance that made this a bad hide. Recently (so no logs knew about it), wasps had begun building a honeycomb attached to a cache. Essentially, the cache was resting on a screw, in a sign, and was plainly visible, and just like the others in the series hidden just like it. However, the wasps had begun construction hanging off of the screw the cache was on. So I swaggered up to it, removed the cache, and after signing the log, realized the extreme wasp activity going on in the sign. I then looked through the screw-holes, noticing the wasp comb, and debated on whether to replace the cache in the hiding spot (risking stinging of myself and the next people to find the cache), or remove it (which the owner probably wouldn't like). I decided to replace it and immediately contact the owner about it, so I basically got posed to run, plopped it back into place, and sprinted about 40 feet away. I must have gotten some strange looks from muggles, but, no stings! (And yes, the owner has been contacted and knows about this now)