I never believed china numbers and until now with every moment that passes it seems that I wasn't wrong.
Okcoin has been caught twice faking numbers so it's huobi next.
II remember too well when btcchina was claiming 4 times the volume with 1/4 of the orderbook gox had.
For my part, so far I have seen convincing evidence of fake trade at Mt.GOX, and now at BTC-China.
The first time I paid attention to Bitcoins was when Rick Falkvinge (founder of the first Pirate Party) tweeted a glowing endorsement, announcing that he was investing all his savings into Bitcoins. And the first time I heard abot Mt.GOX was around Dec/01, when Rick denounced them for replaying the same transactions over and over while the price was actually falling through the floor. (If it was a bug, it was a very convenient one...)
People have claimed that most of Huobi's volume is fake, but I am not convinced yet. Note that a transaction, whether by hand or by robot, is not fake if it entails an exchange of money and bitcoins between two competing traders.
Huobi has lots of robot trade and thinly sliced orders, but I have yet to see convincing evidence of fake transactions. For one thing, their volume is nearly zero after midnight, lower at holidays, etc. (Mt.GOX's "ping-pong" robot, in contrast, ran continuously for days at a steady rate, stopping and starting abruptly.)
(BTW, Rick later retracted his endorsement of Bitcoin, after he realized that transactions are not at all anonymous and untraceable, as bitcoiners used to claim.)