Gnani will not show off nor boast; for he wants to appear a normal man, not an extra-ordinary one.
The ordinary person thinks "this is a wall"; "that is a man" etc. whereas the Gnani thinks "this is Brahman, he is Brahman." etc.
It is said in Mandukya that even the Gods cannot find out who is a Gnani, because he bears no external mark. Neither nudity nor the yellow robe has anything to do with him.
Sri Krishna himself says that he can do nothing to make a man intelligent straight away. The adepts give prasad, blessing, initiations, mantrams, etc. only to confer temporary peace of mind, to help you to get rid of worries, but not to confer Gnana. The capacity to receive it, must first be inborn in man by evolutionary degree.
The teachers leave their experience behind in scriptures and books, as a legacy to posterity. They know that books are illusory, but they also know they will be useful as a means of progress from lower to higher ideas of truth.
Sahaja-Samadhi is for the Gnani, yoga-Samadhi is for the mystic.