I think it is possible to see a teacher mundaine by focussing too much on the outer form. It then is difficult and we can need help and checking work to know about the master genuine practice. Still focussing merely on all substantial achievements, papers, famousness, is a bit a kind of mundaine habitual doing.
There are practicioners who turned in a blow of, sorry to use that word again; devotion, and prostrate for the Guru. But they didn't see the Guru in details, maybe a smile of his face was 'experienced', still no fixation to see the human appaerance, neither to feel ones' body prostrating. A faith flowing as faith in once own nature.
There were-are practicioners who meet masters their blessings, without knowing their name, without anything more then pure selfless love. Then there is no name to cling to neither. Easy, one job already done.
There is lots of talk about wrong ones, but what is so important is to not lose trust in ones genuine master, or to make others lose trust in their master. At least we can rejoice for all of us, meeting the Buddhas' teachings.
Blabla...Sure, one difference between beings like me and emanations is that I have so much cleverness to say and they only 'talk' to awaken.
PS Right now, just reading blue Garuda post, we may say NO to the master, isn't? We should do so when we feel not to understand his meaning, or when we doubt in practice whether genuine or not... Then we politely can/must say that or repeat checking....