I'll tell Roy he fell off the changing table, she thought. He'll believe that. Oh God, let him believe that. (3.44)
Most of the townspeople's lies involve sex; Sandy McDougall's is one of the few that's about violence. The fact that she beats her baby is one of the uglier secrets in the book. Her corrupt little family, seething with anger and casual brutality, seems more peaceful when they're all vampires, hiding secretly under the trailer in the twilight world.
"…if you're doing anything illegal up there, I don't want to know about it." (3.228)
Lawrence Crockett knows that Straker and Barlow are up to something. He may not want to know what he's going to conceal with his lies, but he knows he's going to lie to conceal something.
"Meetcha," Jackie said, and disappeared into the dimness. (5.142)
Jackie serves drinks at Dell's place; this passage is about the first time she shows up in the novel. Before she appears though, the novel reveals (via Lawrence Crockett) that she's sleeping with Hank Peters (who has a wife). So really the only thing there is to know about Jackie is that she has a secret—a lie is all she is as far as the novel is concerned. She's only there so the reader can know that she's concealing something.
He thought of the Bowie girl—no, McDougall, her name was McDougall now—saying in her breathy little voice that she had hit her baby and when he asked how often, he could sense (could almost hear) the wheels turning in her mind, making a dozen times five, or a hundred a dozen. Sad excuse for a human being. (6.295)
Again, Sandy McDougall has an evil secret, which according to the novel makes her a sad excuse for a human being. And soon she'll literally be a sad excuse for a human being… in that she'll be a vampire. So everything works out on a symbolic level.
"Matt, do you know what's going to happen to you if you even let out a whisper of what you've told me?" (8.115)
Ben is telling Matt he needs to lie to the authorities or people will think he's insane. The vampire hunters actually end up telling a lot of whoppers to keep the police off their backs. It's almost like they're in cahoots with the vampires, helping them hide so that the plot can rush along.
… George Middler had a suitcase full of silk slips and bras and panties and stockings and that he sometimes pulls down the shades of his apartment over the hardware store and locks the door with both the bolt and the chain and then… he falls to his knees and masturbates. (10.10)
Vampires often symbolize lust (see "Themes: Lust"), and so many of the secrets in this book are sexual secrets. The book says little about George Middler except that he dresses in women's clothing secretly—and later it's suggested that he's a homosexual and a pedophile. Linking homosexuality and cross-dressing to evil, vampires, and pedophilia wanders uncomfortably close to homophobia, though it's worth mentioning that in 1986's It, King explicitly condemns homophobia.
"You're lyin' to me," McCaslin said patiently. "I know it, these deputies know it, prob'ly even ole Moe knows it. I don't know how much you're lyin'— a little or a lot—but I know I can't prove you're lyin' as long as you both stick to the same story… I'd take you down just the same and put you to the inconvenience except I get a feelin' you ain't lyin' because you did somethin' against the law." (11.407)
Again, the vampire hunters have to lie to the law. Shortly after they refuse to tell Sheriff McCaslin about the vampires, he becomes a victim himself, leading Shmoop to wonder if lying was really the best way to go.
"And you came here alone?" she asked when he had finished. "You believed it and came up here alone?"
"Believed it?" He looked at her, honestly puzzled. "Sure I believed it. I saw it, didn't I?"
There was no response to that, and suddenly she was ashamed of her instant doubt (no, doubt was too kind a word) of Matt's story and of Ben's tentative acceptance. (12.27-29)
Mark is honest and straightforward, but Susan, the passage suggests, is deceiving herself. The vampires seem to rely on folks' self-deception even more than on outright lies. People lie to themselves about evil, which is how evil gets them.
Some of them had emerged enough from the shadows of death to have regained some rudimentary cunning… Glynis Mayberry called Mabel Werts, said she was frightened, and asked if she could come over and spend the evening with her until her husband got back from Waterville. Mabel agreed with almost pitiful relief, and when she opened the door ten minutes later, Glynis was standing there stark naked, her purse over her arm, grinning with huge, ravenous incisors. (15.12)
It's not really clear why the vampires need rudimentary cunning. They got people easily enough by just going out and getting them before they had the run of the whole town; why couldn't Glynis just head over to Mabel's window and hypnotize her into opening it? The answer is probably just that it's fun to read about the tricksy vampires and their sneakiness. Lies and deceit are seductive and, in this case, funny.
The town kept its secrets and the Marsten House brooded over it like a ruined king.
Hubie Marsten, with his evil secrets—and evil secrets within secrets—is a prototype of the town. The darkness lurking behind his windows becomes the darkness lurking behind everyone's windows.