A guru considers himself to be representative of his own guru and never asks his followers to worship him like a God. In fact when some of Srila Prabhupada’s disciples out of sheer ignorance started worshipping him as God then Srila Prabhupada became very upset and he immediately asked them to stop this nonsense, in fact he heavily chastised them for equating him with the Supreme Lord. A guru never takes any credit for his any achievements, whatever he gets he offers it to his guru and his guru offers it to his guru and so on. So, finally all credit goes to Krishna. Srila Prabhupada dedicated all his accomplishments to his guru, Srila Bhaktisiddhanta Saraswati Thakura.
Through his wisdom words, a guru nourishes the intelligence of his disciples and of general populace helping them to understand their relationship with the Lord and how to again re-establish that forgotten relationship. He preaches by his own example, in fact he walks the talk. He follows the process of devotional life as given in the Vedas and imparts knowledge which is in line with the teachings of Vedas. He neither invents any new methodology to attain love of God nor does he concoct his own philosophy. Through his deeds he inspires and motivates people to become sincere devotees of the Lord. He associates with saintly people to discuss the spiritual subject matters and not with worldly people. His attire is always simple and devotional and his means of living is honest.
So when we see someone dancing on a movie song or intimately hobnobbing with members of opposite sex or having a lavish lifestyle or speaking words not befitting a devotee of the Lord then without any hesitation we should understand that he is a fake guru and should be outrightly rejected.
A guru is Krishna’s external representative and the internal guru is Krishna Himself situated in everyone’s heart. Through his purity, devotion and expert guidance a genuine guru illuminates the life of his disciples by removing all ignorance from his life and reveals the path treading on which one can go back to Krishna, the Supreme Personality of Godhead.