Some models are exported using a different bone rotation (primary axis) than what Blender uses by defualt. This makes them appear as if they were all rotated wrong.
This is very common for models exported in Maya but nothing of this is conceptually wrong, just a different standard used also by some game engines (like Unreal Engine) and the fix is just one click in Blender.
For my examples, I will use the Novabeast model FBX.
While on the FBX import window select this one option
