Thank you for posting the interesting comments on pump and dump scams.
So, it seems that the important warning sign is look out for thinly traded stocks with very low average trading volume (100-day period). Thus, enter a thinly traded stock with caution, because you may be the next mark to be rolled in the Wall Street green felt jungle.
By the looks of CMGI (CMGI Inc.) trading volume, pump and dump schemes could be spotted on this message board and the trading volume would be very difficult to pull off. I generally do not trade a stock that has less than 1 million average trading volume over a 100-day average period.