The devotee should avoid a person whose character is not fixed in the standard understanding; even though he may be a Vaisnava, or a devotee of Krsna, if his character is not correctly representative, then he should be avoided. One should steadily control the senses and the mind and strictly follow the rules and regulations, and he should make friendship with persons of the same standard.

Srila Prabhupada; SB 3.29.17 purport