There are many exchanges that are faking volume. Some reports show that there is up to 90% wrong volume reports. With market developing i am sure there will be more strict rules and penalties.
I think this is the next step in crypto for further development.
There should be some index be issued based on volume to track real volume of top 10 or top 20 exchanges who should be then monitored by some external company.
I hope also CoinMaketCap will take this issue into consideration soon enough to get some real data on smaller exchanges as well.
Coin market making profit from the trading sites so they are going to you stay with the favour of them not with the uses because they are giving this service for free. But it is better to give the the right thing what they are doing rather than asking their reputation for money and they even climb that they just reporting volume from the exchanges so we need to have verify the value true or not.