Your successful double-spend shows up on this site that tracks them:

http://respends.thinlink.com

It's true that double-spending a 0-conf tx is easier than most people think, and it's true that you should be very careful *ever* trusting a payment with no confirmations.

The weird thing is the idea that no effort should be made to improve the situation, or at least let the victims know sooner.  The reason that comes up is "it won't work 100%, so don't even try."