It would be great for guilds if there were serial numbers placed on raid gear drops (if possible). So if a person was selling raid gear meant for guild use only, they could be easily identified and disciplined. I realize that this is only needed up to PoP when drops are all no drop, but still it would help during Classic and up to PoP.
Norrath isn't that big. When folks do stuff like that, it usually doesn't take long at all for them to be identified.
Are they now? It's been ages since we'd had an issue that I had passed on as a Guide like that but it certainly wasn't that way back in the day - they had to pour over logs and follow when it dropped and all the transfers throughout - it wasn't just a simple S/N lookup. Unless my server GM just liked to make excuses back then - it was an involved process. (She normally had around a 2-3 day turn around on such things)