He is a proper Sadguru to when your mind is attuned . He should be endowed with tranquility, patience, forgivness, and other virtues, he should be capable of attracting others even with his eyes just as a magnet attracts iron. He should have a feeling of equality towards all. He who has these virtues is a true Guru.—-Maharishi Ramana.
According to real Saints these qualities should be in Sadguru. In Upnishadas and Guruvani it has been clarified in so many books. and Maharihi Ramana was a living Guru he told his own qualities. we as desiples or seeker of truth should know this. In these days there are so many false Gurus in all over the world especially in India. My Guru, Saint Nikka Singh ji was like this real Guru. but as Sri Shankarcharya defined it in his Bashaya on Gita. He wrote that Gurus gave these ideas to followers in their mind while practicing. When he will find this stage, then he will satisfy. otherwise he understand about any Saint that he perfect or not.