Factual error: In the opening scene and throughout, young Sam Anderson, cloistered in his bedroom, is presumably listening to a crackly 45 rpm copy of Nick Lucas crooning his 1929 hit, Tiptoe Through the Tulips. In reality, the disc with gold/blue label spinning on Sam's turntable is not the song playing. The original Tiptoe was released in 1929 on 78 rpm vinyl by Brunswick Records, and was finally pressed on vinyl 45 by Accent Records in 1974 (solid robin egg blue label however, not gold/blue).
Continuity mistake: The Wolf is shown to have filthy teeth but when Carol confronts Morgon in The Cell, his teeth are clean.
Answer: Walkers are attracted to noise, they can tell who's dead and who isn't dead, in S1 when Rick and Glenn cover themselves in walkers' guts they're able to get far by walking through the herd of walkers because they smell like they're dead, but as soon as the guts get washed off by the rain the walkers immediately attack them, if you draw attention to yourself they will attack you which we've seen that many times throughout the series that it's not always successful. Whether you're covered in guts hiding under dead corpses or under a car.