I remember a long time ago there was a patch that stated that the enhancement system was improved in a way that if you have a lot of fails in a row, the success rate will go up. For that to work, you supposedly have to keep the enhancement window open.
However, after how many fails will this supposedly improved success rate be triggered, and what that new success is going to be will never be disclosed. For all we know, it could very well be like this: if the success rate is, say, 1%, you will need roughly 100 attempts to get a success; with this new "improved" system, after 99 failed attempts, the next attempt will 100% be a success. Big improvement.
So, the players want the enhancement system to be improved and become more fair and balanced. Do they get it? No! Instead the blame for failed enhancement is put on them. You had many failed attempts. Did you close the enhancement window? Well, there's ya problem! Did you enhance when many other players were also enhancing? Tsk, tsk, tsk, big mistake.
Even if these reasons for failed enhancements were true, which I highly doubt, they are absolutely unacceptable, because it is not explained anywhere in the game while you try to enhance.
So, why is it all so vague and hush-hush? I really wonder.