It sounds like you are describing feline acne or dermatitis.
The current favorite topical treatment for feline acne among some veterinarians is 2% mupirocin (Bactroban Rx) ointment, used twice a day for three weeks. You should also evaluate the food bowls and water dishes. Some cats have allergic reactions to metal bowls and you will see lesions that look like acne but are not. If the bowls are not cleaned well, it also might be a bacterial problem.
Sometimes there aren't any pustules just black grainy/sticky stuff around the lips that scrapes off easily - sort of like blackheads gone wild. You can try cleaning it up with alcohol at home - sometimes that is enough to help if there is no other inflammation or pustules. Calendula gel is a good antimicrobial and skin healing promoter. Plastic bowls can cause a contact dermatitis also, but this sounds more like acne.
Your vet can quickly diagnose this for you and discuss your treatment options.
Let me know if you still have questions.