As any first-year statistics undergraduate could tell you, if you want to find out whether customers prefer GM or conventional corn, putting a sign saying, "Would you eat wormy corn?", over one of the bins makes the results worthless. The paper describing the work should not be allowed to remain in the literature, yet the authors refuse to withdraw their paper, offering instead less and less plausible accounts of what happened to the sign.
You'd also think this was just the sort of thing that the various groups who have set themselves up as the guardians of "sound science" would be very concerned about. In fact, they have said nothing.