Then why do I see other ppl with oily skin dirty n no acne

It all depends on the size of the pores and how strong ur immune system is

At its root, adult acne is caused by the same things that cause teen acne: excess skin oil and bacteria. Any changes in hormones, including those brought on by pregnancy and menstruation, can trigger excess oil.

Acne tends to run in families, so if a parent had adult acne, you're at higher risk. People can get acne into their 40s and beyond.

I agree. That acne is linked with teens and highschool is just an urban myth.