i think the "net affect" of a single person bashing or pumping is pretty minimal. simple bashing like "you're an idiot, this stock is garbage, they have nothing to sell" may discourage new retail investors from entering but it often has the opposite reaction with many individuals (i.e. "i'll show you who's an idiot! i'll buy more")...human nature, crazy stuff.

i always look for the one true giveaway in the market. when everyone is screaming "buy!! it's gonna explode!" and you cant find a negative opinion anywhere then it's time to start looking at selling because everybody is already fully loaded..i guess that's the "contrarian" in me..