Unfortunately, some of the stronger and more tacky-feeling cleansers just sit on the bowl, inside and out, and the surfaces never get clean. Cleaners with fewer ingredients, such as more natural or homemade products with citrus, vinegar or baking soda compounds, may be worth a try. Liquid castile soap is another option. Generally, these go on thinner and may require a little more elbow-grease at the start of using them, but over time they prevent malodorous buildup.