Do rubber mousepad bases stain white desks?

Yes, especially cheaper rubber bases. Plasticizers in the rubber can migrate into white laminate or painted wood, leaving greasy yellow stains. Silicone bases are better because they don’t need plasticizers, but look for “100% silicone” to avoid blends. Heat and sunlight speed up staining, so keep the desk cool. Spend extra for a silicone pad to keep your white desk clean.