Well, they have a good history of being shady. I haven’t checked their fake volume or not, it's something most of the exchanges practice these days. I wouldn’t be surprised if they are doing that too. It’s quite common regardless of how shady it is.
However, they have something beyond this too. We all know how Dogecoin has been pumped in last year. Sadly, hitbtc was one of them who censored the price DOGE a lot in their exchange and forced everyone to sell their coin at a lower price.
When DOGE pumped significantly, they had DOGE withdrawal off, which caused people not be able to withdraw their DOGE and sell on other exchanges.
On the other hand, the price of DOGE was half of the actual price on other exchanges. For example, when DOGE was at ATH of $0.73 on other exchanges, it was around $0.40 on hitbtc. It’s because they had off the withdrawal and censored the price of DOGE, as a result, users were forced to sell their DOGE at lower price (market price in hitbtc) which I have mentioned already, was half of the actual price.
This proves how stupid they are, how shady they are.