Dirty hair can cause chest and back acne, is that true?

Why do you ask?: Despite "pop" wisdom, acne has little to do with personal hygiene. Beyond giving you a heads-up that poor hygiene is a grave personal and professional liability (like acne), your chest-and-back acne won't clear as you clean up. Trunk acne won't respond well to anything short of systemic treatment. If topical benzoyl peroxide plus a systemic antibiotic doesn't clear you, consider isotretinoin.