(Update 06-13-2020) The links below no longer work. This is one nature of the internet: nothing lasts forever. Here is a new article Tang Wei Zhen.
Couple points to spot warning signs:
1) If something sounds too good to be true, it IS too good to be true;
2) If someone claims he/she can predict the market, run, not walk away from him/her;
3) (Specially apply to Chinese) If someone claims to be Chinese Buffett, obviously he/she is Madoff.