If I wanted to go fishing for a nuclear sub (or simply increase the likelihood of a collision), all I would need to do is find where they like to hang out (where are the most detailed maps of the ocean floor?) and drop some interesting bait (say a steel drum with alarm clocks inside).

Is is possible to determine whether either of the particles has been changed to a 'defined' state without 'defining' its state ? Has someone already peeked into the cat's box ?

Paint the object you want to hide and point the image source (camera) at whatever is behind the object.

I totally agree - for all we know, one of the particle accelerators on planet earth may blink us all into non-existence before I finish typing this. Our 'selfish genes' would be most disappointed if they didn't at least have a distant cousin to continue the 'life' experiment.