Whenever I read a negative review like this, I wonder whether the author took an advance short position in the company he's reviewing. It's legal -- it doesn't

Whenever I read a negative review like this, I wonder whether the author took an advance short position in the company he's reviewing. It's legal -- it doesn't count as insider trading -- but it's a bit shady if true. It's not that uncommon. It's the opposite of "pump and dump", but it has the same outcome -- those in the know benefit at the expense of naive investors. This isn't to say the review is wrong -- it seems to be right -- but if the author has a short position, that fact might color readers' thinking. Just speculation -- I don't know if any of this is actually so.