I personally don't see how making a cache "Members Only" can in any 
way alleviate the problem of "plundering."  I imagine that most caches 
that are plundered are done so becasue they are stumbled upon 
inadvertently. (I've seen no data to suggest otherwise.)  If this is the 
case, then I think it is a function of the cache locale more than 
anything else that makes it more prone to being plundered.    The 
alternative would be to believe that someone is actually selecting 
caches from the GeoCaching web site and purposely tracking them down to 
steal booty from them.  While I'm not suggesting this can't  be the 
case, I think if someone were doing it, then cache plundering would be a 
much more widespread problem than it is.  Making a cache "members only" 
 wouldn't deter this kind of pre-meditated theft.  If  someone were 
predisposed to such dishonesty, the $30 for a membership could easily be 
offset by plundering a handful of carefully selected caches that contain 
expensive contents.  (Ironically, it seems that these are exactly the 
types of caches that are being made "members only.")   Heck, half a 
dozen ammo cans at $5 a pop are worth $30!  I just don't think "Members 
Only" caches are going to solve the problem of plundering.  
   Perhaps I'm missing something, but I also don't see how the ability 
to "audit" who has read your cache description can help either.  If a 
cache is plundered, does it then mean that everyone who read the cache 
becomes a suspect?  And, since only paid members can read them in the 
first place, then it would have to be a paid member who was guilty of 
the theft.
  In general, I feel that encouraging "members only" caches is simply 
endorsing "elitism."    It then becomes another example of "the haves" 
and the "have nots."  I'm sure that some folks with plenty of disposable 
income have no problem with plunking down the money for the "priveledge" 
of finding caches that others cannot.  Those with a limited income 
probably feel they have more important things to spend their hard-earned 
money on-- like food for their children and such.  Part of the allure of 
the sport of geocaching for me is that it is, in a sense, classless.  A 
multi-millionaire with the nicest $800 dollar GPS and a Humvee that will 
drive over mountains has as much chance of hunting for and finding a 
particular cache, as someone who has to borrow the cheapest GPS there is 
from a friend and ride a bike or walk to cache.

Just my $.02
-- Sprocket