Found an interesting article in which one guy did some datamining on some popular exchanges and their volumes:
https://medium.com/@sylvainartplayribes/chasing-fake-volume-a-crypto-plague-ea1a3c1e0b5eApparently a few of these giants are falsifying their volumes. Maybe because a higher market cap would make people think it's a more trustworthy exchange? I don't know if it's really worth going through all of that effort.
Would this have a major effect on the prices? I know we used to see huge differences in prices in the past, but now you won't see much more than a few percent here and there between exchanges.
If the volume is fake, it might not affect the price, I also see some crypto markets, having high volume and low volume, but still not affecting prices.