Anyone with discerning taste and a love of beauty products knows that a lot goes into picking a good lipstick, foundation, or even hairspray. Pro recommendations are key, as are reviews , but at the end of the day, there's one thing that we often forget to consider: What the masses are buying.To find out, we tapped seven major beauty e-tailers to find out just what's been flying off the shelves lately. Our logic: If thousands, or tens of thousands, of our peers are obsessed with something, it must be amazing — and we need to know about what's amazing.Ahead, you'll find 28 products that stores like Net-A-Porter, Sephora, and Amazon simply can't keep stocked on their e-shelves. Call 'em what you want — best sellers, customer favorites, regularly OOS (out of stock) — just be sure to add them to your cart while you still can. We officially give you permission to follow the crowd on this one.