Strife-filled labor relations tend to damage product quality. The deterioration is sometimes so serious that "it would be useful [for consumers] to have products stamped, 'Made during a strike,'" says Princeton University economist Alan Krueger...As evidence of this thesis, Krueger cites what happened at the Bridgestone/Firestone plant in Decatur, Ill., during a long contentious labor dispute in the 1990s.