Buying skin care products can be so hit-or-miss: You can stop at a drugstore, and hope the cleanser you select isn't designed for an acne-prone teenager, or you can visit a big-name cosmetic counter at a department store, and hope the salesperson isn't out-and-out lying to you. At Sephora, however, the selection is vast, the salespeople are incredibly well-informed -- and none of them works for any one cosmetics line. So imagine, for example, you want to try some vitamin C serum. After you've browsed a little by yourself (products are displayed on open shelves), you can find a salesperson and start asking questions. He or she will have attended specialized training seminars on all the product lines, and will be able to explain the pros and cons of Cellex-C's formulation vs. the one made by Peter Thomas Roth vs. DDFs' version in such detail you'll feel you've practically been to the company's research labs yourself. And, if you still have doubts, you can even ask for a sample to take home so you can try before you buy. One note: The salespeople downstairs, in the skin care department, are far, far nicer than those upstairs in makeup, who, not to put too fine a point on it, can be extremely bitchy. You have been warned.