This is such a key skill. It's important to judge whether a person is open to feedback or not. A lot people assume others are open to hearing criticism. If your manager is a narcissist and you start pointing out things that they are doing wrong without earning their trust you are as good as toast.
Doesn't mean you are sleazy, but if it doesn't make you look better to say or make you friends, don't bother say it. Let that open to the internet server slide if it requires blaming someone higher up.
Would have to disagree on playing politics, unless you mean minding what one says. Office politics aren't worth the energy or the toll they take on one's morale and character. If you work at a place where the mudslinging is heavy and often, especially among management types who are toxic and target the ones they manage, gtfo of there.
From experience, if you stay you're essentially letting them rob time from your short period spent alive, and recovering from the trauma is lengthy. Personally, it's taken nearly a year after being laid off to recover and begin feeling like myself from before the ~7 years of working under 2 bosses of this type (one was the vp of tech and the other was a manager below her, so two levels in hierarchy).
I was too trusting - huge mistake from a health and stress perspective
If you choose to build your career on helping others avoid the consequences of their mistakes, then you are part of the problem.