Here is the truth, for me at least. I spent many years and many dollars on expensive products and antibiotics. Nothing worked. It seemed that it got worse as I hit 30.
One year when I was having my annual exam at the OBGYN, the nurse practitioner talked to me about it. Honestly, she brought it up and boy was I happy. She prescribed Ortho Tri Cyclen. My skin
cleared up in three weeks.
I have 3 cousins that are OBGYNs (all out of state). None of them believe that one brand can help over another, but Ortho Tri Cyclen and Tri Cyclen-Lo are approved by the FDA for acne.
After my skin cleared up, I was talking to my aunt. She then told me that when she was in her 30s, the doctor put her on birth control too to clear it up. Evidently, in our family, it's hormones that cause it, not dirt, what you eat or whatever else. I'm not saying that it's for everyone; some of my friends refuse to go on the pill because of fear they will gain weight (says the 85 pound Ironwomen).
If nothing else works, talk to your doctor.