Spam Stock Recommendations

I have often wondered whether, the first time I receive some spam recommending a particular stock, I should buy it. The hypothesis would be that probably a few others would do the same thing. Then I should sell it again soon, maybe even the same or the next day.

Alex Tabarrok of Marginal Revolution draws our attention to Spam Stock Tracker which explores this question among others.

I thought that I would realize temporary windfalls on all penny stocks, but then see big losses. Instead almost ALL of those stocks I added went up a few cents max, then dropped like flies the next day. So much for short term gains.

So why do spammers advertise certain stocks? Are these stocks that the spammers bought previously and hope to unload on speculators?