First of all I feel your pain about not getting good logs. On every cache page we have we state:
"The only payment a cache owner receives is the log that you write on the cache page. We took the time to place the cache so please take the time to tell us about your experience."
We ourselves are guilty of short logs when "power caching" and that activity may be the culprit. Last Friday poppy and rkl snuck off to snag a few caches. We drove to Maumelle then worked our way back to Morrillton and eventually had to leave so that we could be at home for a social engagement nonni had scheduled. nonnipoppy found 41 caches, the next day when logging them an old muddled mind coupled with no typing skills made us created logs that were far to short and less than enjoyable to read. Perhaps we need to rethink our caching.
To answer your question YES you own the cache and have the right to delete any and all logs that you choose to, however; I can not see many positive outcomes from this action. It's just going to anger the finder and then some will retaliate. And then there is a new problem.
We decided to look past those cut and paste logs and enjoy the ones that truly tell a story. Sometimes we have to remind ourselves to step back, take a deep breath, and remember that this is still just a game and everyone plays differently.
Having said all that we had a great time seeking your caches....poppy
May those who love us, love us. And those that don't love us, may God turn their hearts; and if he doesn't turn their hearts may he turn their ankle so we may know them by their limp.... An Old Gaelic Blessing