A dull or uneven complexion can be related to many aspects:
Sleep deprivation- can cause your skin to become dull and pale.
Dead skin cells -not being removed can make skin look dull, dry and flaky.
Sun damage -is also the main cause of weakened skin laxity and a decrease in collagen levels, resulting in dull, patchy skin.
Medical history/Medications- this can play a part in how your skin looks and feels.
A pharmaceutical homecare regime would be advised to lift off any dead skin cells and help brighten the complexion along with clinical facials to create a dewy, brighter, even and hydrated appearance.