Crikey - bit of a horror story that. Obviously far better that it got picked up during a test than through failure in use though.
Sounds like yours has had a hard life in the past and has been willfully tarted up / disguised to be sold.. serves to illustrate how the external appearance of a cylinder really has no bearing on its fitness for use.
Shocked by some of the stories from the dive shop - just goes to show how utterly stupid some people can be
Will be interested to see some pics!