Q. In india there are so many ‘Sampradaya’. They all are Vaishnavas but they don’t follow the ‘Vaishnava principles’ strictly.But they have faith on GOD according to their knowledge and understanding. So how to behave with such devotees? Is GOD really pleased with their worship? In Maharashtra there is such a Sampraday ‘VARAKARI’ Sampradaya. Is this authorised ‘Sampradaya’ according to Scripture? It is said that Lord VITTHAL is KRISHNA himself, but it is not mentioned in any ‘Scripture’. Is it true ?
If yes then what is the pastime of Lord VITTHAL? Plese tell me the pastime of ‘DATTATRAY MAHARAJ’.

A. There are four Vaishnava sampradayas and all of them are authorized and authentic. So, anybody or organization who is in any one of these four sampradayas is to be accepted as bonafide and hence Krishna accepts worship and is pleased with such devotees. The Varakari sampradaya is coming from Tukaram Maharaj, who was initiated by Chaitanya Mahaprabhu and Lord Vittal is Lord Krishna Himself.
There was a devotee, Pundalik, in Pandharpur, who was very devoted to his parents and also to devotees. One year when he could not go to have darshan of Krishna in Dwaraka, Krishna Himself came to give him darshan. But he was so involved in serving his elderly parents that he made Krishna wait on a brick (Vit) till he finished his service. So Krishna is standing in the classic pose of a waiting person and so is famous as Vittal.
We offer respect to all living entities, humans or otherwise and also whether devotees or not. But we associate with bonafide serious and sincere devotees.

In Srimad Bhagavatam 1.3.12, Srila Prabhupada mentions Dattatreya:
TRANSLATION
The sixth incarnation of the purusa was the son of the sage Atri. He was born from the womb of Anasuya, who prayed for an incarnation. He spoke on the subject of transcendence to Alarka, Prahlada and others [Yadu, Haihaya, etc.].
PURPORT
The Lord incarnated Himself as Dattatreya, the son of Rishi Atri and Anasuya. The history of the birth of Dattatreya as an incarnation of the Lord is mentioned in the Brahmanda Purana in connection with the story of the devoted wife. It is said there that Anasuya, the wife of Rishi Atri, prayed before the Lords Brahma, Vishnu and Shiva as follows: “My lords, if you are pleased with me, and if you desire me to ask from you some sort of blessings, then I pray that you combine together to become my son.” This was accepted by the lords, and as Dattatreya the Lord expounded the philosophy of the spirit soul and especially instructed Alarka, Prahlada, Yadu, Haihaya, etc.