Don't we love to receive the emails when people log a find on one of your caches.
If I'm honest it's one of the reasons I hide caches - especially if I know that there is something great about the cache. I enjoy hearing about peoples' experiences leading up to the find. If you place really good geocaches, then expect to receive a lot of positive comments.
Geocachers are usually polite when it comes to logging their caches. If they think the cache is rubbish, they probably won't be too negative; but they also won't be very effusive. You might get some terse comment. If you're not receiving positive comments then maybe the cache isn't as good as you think.
Another way to see what people think is to look through the list of your caches and see how many are marked as Favourites. If there are not many in the list, then maybe you need to review your cache hiding techniques.
Check out the survey to see what people like about geocaches ... then give them what they want!