I can't imagine anyone wants you to rub their scalp so hard it bleeds. Even if they say they like it, don't do it. They have thin skin as the elderly and don't need wounds from getting their hair washed. With HIV, you can not get it during a hair shampoo. You can't get it and couldn't give it that way if you were positive. The only way adults get HIV is from unprotected vaginal or anal sex (penetrating intercourse) or sharing IV drug needles. Transmission takes place INSIDE the body, not from touching any surface such as a person's scalp. So, this is not possible for HIV transmission.