The Boston Globe reports that AMC, National Amusements, and Regal cinema chains are leaving 3D projector lenses on for 2D movies. This means that the projected image is polarized and far dimmer than it should be. The chains won't acknowledge that they're doing it, but one quoted insider says its an "unspoken" corporate policy.
Given that your HD TV set shows it just fine, and your living room doesn't smell of weaponized butter, aren't they driving customers to piracy? Try this for irony: one reason operators hate changing lenses is reportedly because of crippling DRM on Sony's digital projectors, which "will shut down on you" if a mistake is made when resetting the system. So, they just don't change them, because serving a ruined product is better than serving no product at all.