Chinese exchanges were faking volume since they entered the market and there was a shitstorm where their government intervened and shut most of them down in 2014. Some moved to Hong Kong. Do you believe they simply abandoned their old tactic and played fair from that moment? There are exchanges that play fair and those that don't.
Exactly, even prior to the eventual bull-run, Chinese exchanges have been faking their volume, caught by their government, suspended and then an eventual shutdown.
There are one reports that I'm aware of saying which exchanges have been practicing wash trading. Here,
https://www.blockchaintransparency.org/. So this is well-known already, and as much as we have those exchanges doing it, perhaps the best thing to do is stay away with them. And it doesn't mean that BTC itself is fraudulent though. It's just this is a free market, and everyone takes advantage of every situation they can get their hands and make money, sad but true.