> what would you accept as qualifying evidence

Party leadership making apologies for Nazi Germany or support for Nazi/equivalent policies, or tolerance of party members behaving in such a way.

> There's a protocol

OK, so they were not found overstepping the red lines yet, only problematic and dancing on it. OK, this may change in the future. When the relevant institutions make the judgement, then it should credible.

> say you want to create

Sorry, I can't play this game. But you have a point, yes smart Nazis would try to do that.