I read an article in FT this morning about how the Carillion problems were hinted in annual reports going back to 2011 (and also how shorting them was popular throughout 2016 and 2017). Hindsight is 20/20, but there's a real chance that Blackrock are just pretty good at what they do.

Employing George Osborne for squillions straight from government is definitely unethical. How can he act in the best interest of the country when there is a colossal personal incentive to keep BlackRock et al on side during his tenure?

Well, consider TSLA, one of the most shorted stocks of last years. I don't think that Tesla short-sellers are deliberately hiding some information from investors. Jim Chanos, the most famous TSLA seller, is very open why, in his opinion, true tesla price is zero [0] and definitely not hiding anything. Some even argue that Jim is too vocal.

[0] https://www.cnbc.com/2017/12/14/jim-chanos-we-think-tesla-is...