Hides I don't like:
Three consecutive posts that say the log is wet. You look up the owner's profile and he has two finds, one hide, and hasn't visited the site in three months.
The majority of log entries say the coordinates are way off, but the owner doesn't correct them.
Micro's in the woods. Along a trail is OK, but when you combine inaccurate readings due to tree cover with a million places to hide a film cannister, and they get frustrating in a hurry.
Now to get back to the original question, what makes a cache good:
Unique, Creative, Challenging, Location
You notice I said Challenging and not Difficult. For example, Eureka was Difficult, The Judge was Challenging and a lot more fun. (Sorry Poppy)
Of the four aspects I mentioned, I would say Creativity is the key. We have enjoyed several caching trips to Clarksville and have been amazed at some of the "containers".
"Honey, we're not normal people. We're the Griswolds. "