If "promotes people to upper management who don't deserve it" was a disqualifier then you would be left with exactly zero companies to work for. Ultimately you have to be able to tell whether it's a systemic problem or just one disgruntled employee.
Nowadays it may be easier somewhat to get some insight into inner workings, but in 2006 there was no Blind, Glassdoor, etc. Sometimes the positive signals outweigh the negative. In my case they did not.
They’re just people like everyone else, subject to the same psychological failings as anyone.
Giving people a lot of power over other people might just be a recipe for disaster.
Of course I’ve met some compelling leaders and I’ve seen them replaced with total fools so maybe there are people who are better at it than others. (Eric Schmidt springs to mind as an example of the former and Sundar whatever his name is an example of the latter) Maybe it’s just hard to tell the difference. Or maybe our selection process is flawed.