Just to add my 2-cents' worth... I havn't yet found a cache with a decoy/dummy container - but it does sound like a great twist, and IMHO there's no problem as long as the decoy is clearly labelled as such.
One cache I've found consists of a box within a box within a box within... you get the idea. In the teeny tiny box in the middle is a note saying that 'this is not the log book'. The real log book is cleverly concealed elsewhere within the cache. But if you read the online logs, it's amazing the number of people who say 'the log book was missing so I signed and left a new piece of paper'. I feel a bit miffed that I did find the real logbook and yet people who didn't find it, and didn't read the other note, still get a smiley! But then they did find the cache and it is just a game...
Happy geocaching everyone : )
