When people talk about dull skin, they generally are describing skin that lacks radiance or glow like that associated with young, healthy skin. Dull skin tone is typically a result of poor circulation. Common factors that cause dull skin include smoking, excessive alcohol consumption, dehydration and poor diet. Basically any triggers that deprive your skin of much-needed oxygen and nutrients will result in dull skin tone. Lack of exfoliation — the sloughing off of dead skin cells — can also cause dull skin. Dull skin is also often one of the first signs of aging, as skin renewal decreases about 7% every 10 years.