It is recommended that one associate with devotees, but there must be some discrimination. Actually, a sadhu, a saintly person, must be saintly in his behavior (sadhavah sad-acarah). Unless one adheres to the standard behavior, one’s position as a sadhu, a saintly person, is not complete. Therefore a Vaisnava, a sadhu, must completely adhere to the standard of behavior. Srila Visvanatha Cakravarti Thakura says that a Vaisnava, a person initiated into the Vaisnava cult, should be offered the respect befitting a Vaisnava, which means that he should be offered service and prayers. However, one should not associate with him if he is not a fit person with whom to associate.

From Srila Prabhupada’s purport to SB 7.7.32