What's shady about the volume on those exchanges is there are no fees. So actually they're completely irrelevant. This was established TWO YEARS ago. Get with the program.
I agree, on exchanges with no fee, the volume should not be taken seriously. One could simply buy and sell at the same time, and simply fake volume,
which is exactly what's going on now. The main question now is why ? Just to be considered a more important exchange or is there something more to it than just that..
What do you mean why? To be called the biggest Bitcoin exchange! To attract new customers by being the biggest! It's all about the marketing in the world and also in the Bitcoin world!
To be honest, I believe that nearly all exchanges might be inflating their volumes a bit, just to attract the fresh blood!