In reality, if you see, the answer to all the above questions is that very few one's of all those gurus present in the society are those who really have true knowledge of God or who have actually seen the God in reality. Rest all are not fake, but they may have some Bookish knowledge, from where they read & teach you but most of them do not have, in depth knowledge of God.
Great Swami Vivekananda when initially approached for the first time to Great Guru Ramakrishna Paramhansa, he only asked one question from him. Have you seen God? To Swami Vivekananda's question, the Great Guru answered, Yes, I have seen him & I see him just like, I see you.
In Bhagwat Gita also the Great Lord, Sri Krishna says the same about this matter. Below is a good verse, "Verse - 3, Chapter Seven of Bhagwat Gita" teaching the same thing.
kashchid yatati siddhyaye
yat-taam api siddhanam
kashchin mam vetti tatvatah" (Bhagwat Gita: Chapter VII verse 3)
“Sri Krishna said: O Arjuna, Of thousands of men some rare soul strives to realize Me & endeavour for perfection, and of those striving Yogis, again, someone rare one (devoting himself exclusively to Me) knows Me in reality."
So if you have some Guru or you know of a great soul whom you revere as Great Godly person, then be sure that your Idol person, really has knowledge of God & has realized Him in life. Just check, whether he is the real rare Gem who knows God in reality & can lead you also to God.
Jai Shri Krishna