Failure of dried paint to obscure or "hide" the surface to which it is applied.
Use of low quality paint.
Use of low quality tools/wrong roller cover.
Use of an improper combination of tinting base and tinting colour.
Poor flow and leveling (see Poor Flow/Leveling).
Use of a paint that is much lighter in colour than the substrate, or that primarily contains low-hiding organic pigments.
Application of paint at a higher spread rate than recommended.
If the substrate is significantly darker or is a patterned wallpaper, it should be primed before applying a top coat. Use a top quality paint for better hiding and flow. Use quality tools; use the recommended roller nap, if rolling. Follow manufacturer's recommendation on spread rate; if using tinted paint, use the correct tinting base. Where a low-hiding organic colour must be used, apply a primer first.