in my opinion a good and good exchange presents a lot of factors including the volume of sales, the number of coins listed and the low fees that can be a good exchange and attract many investors or traders to be there.
The trading volume can be manipulated, it cannot be a factor that makes an exchanger a good exchanger. so I continue to argue that security and service for 24 hours a day is the most important thing in an exchanger to be said to be good.
That could be true, I read an article about that and I like to share it here, you can refer to the link below.
https://www.theblockcrypto.com/2019/05/28/up-to-86-of-total-reported-cryptocurrency-trading-volume-is-likely-fake-according-to-analysis-of-exchange-website-visits/That would mean only few exchanges in the market are reputable, and we should trust them over the questionable exchanges.
The record I saw recently shows that we have only 10 exchanges with reliable figures, which means the remaining ones are being manipulated at one point, though it doesnt mean that all the volume are typically fake, but at least 40 to 60% of it are fake. There are some of the exchanges that has finally convinced people through that and gotten at least 90% of real volume.
This practice is a very bad one because it misleads investors, but at the same time, I would not completely judge them since the only way to encourage people is through volume, we traders likes to stick with volume more than the exchanges features, so we deserve what we get sometimes.