To add to themainmain's thought, it is a known fact that short traders work in packs, thats how they make their money.
The flip side of a short trader's risk, companies know the games they play and history has shown that a company in the right financial position could form a plan to take their money-bets away from them in order to boost company share price.
This is why the short traders need to monitor all news closely, including monitoring the chat-boards looking for any clues/hints that they should cover their short positions quickly before taking a financial beating.
I personally believe that short traders are pure gamblers, the same kind of folks who are addicted to casinos.