We will never know that “They Live” among us until someone either invents the “sunglasses” or finds a box of the “sunglasses” in an abandoned church next to an itinerant labor camp in Vegas...
YouTube has a great clip on that at "Sunglasses".
One of the most chilling lines, IMO, was when one of "Them" catches on and rats him out: "We have one who can see."
There's also a great, and believable, scene where he confronts one of the upper class who has sold out and pefrectly at ease with it. The original had "Them" using us as a food source, but Carpenter's take was a sendoff on Earth being exploited as a Third World country by the aliens.