As any dermatologist can tell you, acne sebum is caused by excess production of oil by the sebaceous glands, (acne sebum!)which clogs skin pores and leads to the accumulation of dirt and bacteria. The accumulate oil, dirt and bacteria then inflame the skin and cause an infection that bursts through to the surface of the skin, forming blackheads, whiteheads and pimples. acne sebum can attack various parts of the body, but the face, back and chest are some of the most common places for acne outbreaks. Acne comes in mild and severe cases, and the severe cases may cause permanent scarring. Self-esteem and confidence may also be affected by acne's impact on your appearance.