This home in the Bellaire neighborhood of Houston has young children. I’m going to direct the blame for the streaks and drips and stains on the wall toward those children.
You may need to enlarge the photos to see what I’m talking about, but there are stains on the walls probably caused by splashing water (water turned on too hard, people shaking their hands after washing or reaching for a hand towel), or cleaning agents (housekeeper sloshing liquids).
Once the new wallpaper goes up, everyone’s going to have to be more careful and tidy. Water and Windex will stain wallpaper just as easily as they will stain a painted wall.