The Pixel 2 XL display has a consistent "dirty" grain to it, and you can see it all the time if you know what to look for. But the dirt is most noticeable in a dark room with the screen at 0-percent brightness, which is a totally normal, "night-time" use case. Any time there's a solid color background—like, say, in a list with a white background—you'll see the grain. It jumps out when you're scrolling, when the text moves but the layer of grain is stationary. If you're not in the "night-time" scenario, the grain is much less noticeable. But if you look closely, especially during scrolling, you can see it is always present.