There have always been hints and exploits close to a dupe posted on OC, it's just a matter of trawling through old threads to find them, and then putting together the clues. The main factor is simply how much time you have to test things, but your understanding of game mechanics (basically how much/long you've played WoW) and people you know/general intelligence can help find it. I mean, there are only a certain amount of combinations of different bugs you can try to make a dupe, so it's just a matter of time until you have the right idea. They tend to be similar to previous dupes, such as the semi-confirmed one in elite atm. Researching, knowing where to look and understanding what can cause it just speeds up the process. Also, if you know code related to WoW (or another language e.g. Chinese - think of how many D3 dupes have been posted on asian sites) then that's a bonus. If you really want to find it that badly you'll stop begging and spend time finding it
Good Luck!