Important qualification: Narrators associated with innovation do not all receive one undifferentiated ruling. Al-Nawawī records agreement on rejecting reports from one whose innovation amounts to disbelief; for non-disbelieving innovation he reports blanket rejection, conditional general acceptance if the narrator does not deem lying permissible, and a distinction between advocates and non-advocates.
The widely preferred qualified position rejects narration from an active propagator of the innovation, while a non-advocate may be accepted subject to the other transmission requirements. Even among non-advocates, scholarly qualifications remain. The inquiry concerns integrity, truthfulness and advocacy, not simply a sectarian label.