I have really bad dandruff and no shampoos seem to work?

There are ways. If you have tried otc tar, salicylic acid and selenium sulfide containing shampoos, and did not work, it's time for you to see a doctor to try topical ketoconazole or steroid. Bad drandruff is usually caused by seborrheic dermatitis, which is thought to be related to fungal infection. There are ways to control it.