Once again, contact with moisture is the culprit here, though water-resistant varieties of wallpaper are less likely to become wet and develop mold. Using a high-quality exhaust fan or dehumidifier and leaving the doors or windows cracked after bathing will keep this issue at bay. 

Yes, many types of peel-and-stick wallpaper can be used in bathrooms, especially those made of vinyl or polyester. However, its success depends heavily on the level of moisture and ventilation. In bathrooms with good ventilation, such as those with fans, it can be a durable option. Peel-and-stick wallpaper may not adhere as well as traditional wallpaper in very humid conditions. For bathrooms that see a lot of moisture, like a kids' bathroom or a full bath with a steamy shower and poor ventilation, even high-quality peel-and-stick wallpaper is likely to peel over time.

Many types of wallpaper exist, from removable peel-and-stick options to more permanent options that involve pasting. You can also find wallpaper that you can paint over, wallpaper with a texture, and wallpaper made from various materials, such as vinyl. Some types of wallpaper are washable, which can be a great option for kitchens or if your household has small children.

Your peel-and-stick wallpaper can fall off for multiple reasons, including high humidity levels, extreme temperature changes, poor installation, and even the wall surface. Textured walls can prevent the adhesive from fully sticking to the wall, making it more likely for the wallpaper to peel off. Low-quality wallpapers with weaker adhesives are also more likely to fall off prematurely.