Oil-regulating cleansers and face-washing products contain either salicylic acid or exfoliating clay to help skin combat oiliness. Both ingredients are primarily used in products designed to clean the skin by removing dirt and dead skin cells that clog pores and lead to acne and excess oil production.
The salicylic acid and the exfoliating clay don't actually remove all the oil on the face because removing all the oil dries the skin, causing even stronger oil production by the sebaceous glands. Instead, these ingredients help stave off any oil in excess. The clay coats the skin like a light adhesive and brings cells, debris and oil with it when washed off. The salicylic acid has anti-inflammatory properties, which helps open clogged pores and flush the dirt stuck within and the oil on the surface.