First of all, the benefits of this practice are not certain. Modern shampoos do not leave an alkali buildup like that which would have dulled hair when soap or shampoos which were not pH balanced were used. (1) Vinegar's not expensive, though, so give it a try as long as you don't have hair dye or chemical treatment. It can be done two ways. First, you can put about a teaspoon on your head and massage it into the scalp, then wash your hair normally. Second, you can make a vinegar-water mixture of about one part vinegar to four parts water and rinse with it after you shampoo. (1) http://www.snopes.com/oldwives/hairgrow.asp

I don't know the answer to that question (though I would think it would be harsh on the hair and or potentially irritating or drying to the scalp). I do have an article of hair tips from Paula Begoun you might find helpful. http://www.cosmeticscop.com/hair-care-solutions-avoiding-bad-hair-days-tips.aspx Instead of using something to get rid of buildup, I'd recommend getting a product that doesn't create buildup in the first place! Check out Paula Begoun's product reviews on her website cosmeticscop.com. The website only has some of her thousands of reviews, to see them all get her book at the local library Don't Go Shopping For Hair Care Products Without Me. Paula Begoun thoroughly reviews thousands of products in the stores, all the major brands. Each review looks honestly at the ingredients in the product, how good it works, what it does to the skin or hair, and how good of a product it really is. She gives it a rating and includes the standard price for it. She has saved me so much money (by avoiding trial and error w/ products), and in fact her own product line is so good that i get all my hair, makeup, and skin stuff from her! "With more than 25 years of extensive experience in the beauty industry, combined with in-depth research and study of skin and cosmetic ingredients, Paula has the knowledge and expertise to develop truly extraordinary, state-of-the-art formulations for her own line. Paula guarantees that her products meet her exact criteria for excellent skin care, and she won't make any exaggerated claims about them. Her goal is to help women obtain and maintain the skin they've always dreamed of having." Everything she says about her products is true, from my experience. Try her shampoo: http://www.paulaschoice.com/product/all-over-hair-body-shampoo/body-hair-care "All Over Hair & Body Shampoo All Skin & Hair Types Dual-purpose product, works as a shampoo and body wash Creates a rich, cushiony lather Water-soluble formula rinses easily from hair and skin—no build-up! Safe for color-treated hair Suitable for use on babies and children 100% fragrance- and colorant-free" And conditioner: http://www.paulaschoice.com/product/smooth-finish-conditioner/body-hair-care "Smooth Finish Conditioner All Hair Types Daily moisturizing and detangling conditioner that can be used by all hair types, leaving it soft, shiny, and manageable Smooth, silky texture makes it easy to apply and distribute through wet hair Contains no irritating or drying ingredients, safe for sensitive scalps Rinses easily and does not make hair feel heavy or greasy 100% fragrance- and colorant-free"