However, there is no reliable instance of such threats ever having been carried out, though a good many witnesses have gone ahead and defied their warnings. Indeed, sinister though the MIBs may be, they are notable for their lack of actual violence. The worst that can be said of them is that they frequently harass witnesses with untimely visits and telephone calls, or simply disturb them with their very presence

While, for the victim, it is just as well that the threats of violence are not followed through, this is for the investigator one more disconcerting aspect of the phenomenon - for violence, if it resulted in physical action, would at least help in establishing the reality of the phenomenon. Instead, it remains a fact that most of the evidence is purely hearsay in character and often not of the highest quality; cases as well-attested as that of Dr. Herbert Hopkins are unfortunately in the minority.