I agree. But nevertheless I would appreciate having a kind of rating system integrated in Geocaching.com. You are right saying, high quality for one cacher can mean low quality for a different cacher. So why not just calling it a recommendation?
I'd prefer the mentioned TOP10 system but without a sophisticated rating scale. Every cacher can recommend a small percentage of his found caches by simply activating a check box when logging the cache: "Yes, this really was one of my all time favorite caches!". Based on this recommendations you could easily build lists like "Cachers recommending this cache also recommended the following: ...". BTDTNT