“These sorts of unscrupulous actors give a black eye to an already heavily scrutinized industry.”

The passage of the measure ended an ugly, if short-lived, impasse that threatened to give a black eye to both major political parties.

A pair of cases several years into the legal-weed experiment might not seem like much, but they give a black eye to all marijuana regulators and fuel old fears about the criminal element’s influence.

Overly aggressive police give a black eye to the many officers who perform their jobs with bravery and appropriate restraint.

Victor Smetacek, an oceanographer with the Alfred Wegener Institute for Polar and Marine Research in Germany who recently published an analysis of the last sanctioned experiment, which took place in 2009 in the Southern Ocean, said Mr. George’s project would give a black eye to legitimate research.