CS
“You’re right there’s no yetzer hara xray- but you can tell usually from the way a person expresses themselves, whether they struggle with evil or not. If you’ve met/ experienced a tzadik- you would know- they’re on a different plane”
The question was about “how,” but it seems you couldn’t provide a direct answer. You mentioned having a method of knowing, yet it’s not objective and you are unable to explain how it works.
Additionally, could you specify the source indicating that tzadikim no longer possess a yetzer harah?
I’m not implying that “the Rebbe” wasn’t a tzadik, just seeking clarification on your statement.