Rato yes I have and do invest in the Hong Kong exchange stocks, but there are hidden frauds too...for example, the Lin Brothers own Wuyi Pharmaceutical on the Hong Kong exchange, and they shared an office and also own CCME. QED.
That being said, I like some of the state owned companies on the Hong Kong exchange....China Oilfield Services HK:2883 is much, much more liquid than its corresponding US ADR, CHOLY.PK.
The two drawbacks I have about hong kong exchange are (1) finding the news of the day applicable to a particular stock - locals are creating the volume and are trading on the day's events and someone investing from the US has very little idea what is causing their intraday swings at around 11pm or 3am Eastern Standard time. (2) I hate having a 1% foreign currency exchange fee on top of a trading fee of $300 HKD (at a conversion rate of $7.716 HKD/USD).