I got lucky with a discovery of a $1 Columbian souvenir sheet of 1992 that has the tagging missing. I picked up a set of 15 sheets on
ebay and was surprised to note the tagging missing under uv light.
Here is a YouTube video that is instructive on identifying the error sheet. Although they are very scarce, evidently some are still out there waiting to be discovered.
Happy hunting!
http://youtu.be/LPFfCw1kAWQ