it is very unlikely that an exchanger will do this. i think they know to work professionally and certainly won't damage their own reputation.
Exchanges will do everything they can to have themselves rank up based on volumes on sites such as CMC, because that's where most of the traffic comes from nowadays.
Asian exchanges are amongst those who cheat the most with their volumes, where OKEx and Huobi are the absolute leaders in that field.
of course if it is right to do and consumers know, then member will immediately leave it
People know it happens, they simply don't care. As I said above, sites as CMC are very important for exchanges, and for that reason will do everything they can to retain their top 10 spot, because that's what traders look for and consider 'safe' enough. The downside of this is that compliant exchanges can't compete with cheaters because of how much there is to lose for them.
Out of the exchange top 10, 8 exchanges are unregulated. The other 2 might be as well, but I'm not sure. No wonder the SEC isn't interested in this nonsense.