It's one thing when a celebrity endorses a brand. They sign on for a year or two, and their eerily airbrushed photos appear in magazine ads. They tell us in the beauty press about their favorite lotion or whatever the product line might be, but when the contract ends, POOF. They move on to the next big deal and I'm left thinking, "Maybe she didn't like that lotion after all …"

But when a celebrity creates a brand, it's a different story. Stars spend countless hours in the hair and makeup chair learning tricks from stylists and artists. They try a lot of products -- so when something inspires them to create their own line, they generally know exactly what they want.

Some celebrity beauty lines are fantastic. They work well, they smell amazing, they use great ingredients, and -- if they're really good -- they fill a void in the market. Some -- we're looking at you, Snooki -- are flat-out awful. Read on to learn more about the best and the worst of the bunch.

Yes, we're with you: Take one look at Cindy Crawford, and you're saying, "I'll have what she's having." Which, in the case of skin care, is her line Meaningful Beauty.

The supermodel co-created the line with French skin specialist Jean-Louis Sebagh, MD. The brilliance of Meaningful Beauty is its all-in-one, budget-friendly approach: It's five steps plus two "bonus" products (wrinkle-fighting capsules and a brightening serum) -- all for less than $40. And even with the affordable price tag, the ingredients are high-tech: antioxidants, peptides, and hyaluronic acid (fights environmental damage, builds collagen, and hydrates skin, respectively). Not that Meaningful Beauty will make you look like Cindy, per se. But it can't hurt to try.

Star product: Meaningful Beauty Cr�me de Serum, $39.95 for the complete kit

Drew Barrymore's Flower Beauty brand is exclusive to Walmart, and that's just one reason it's impressive: It feels seriously high-end despite cheaper-than-a-cup-of-coffee prices.

Barrymore is involved every step of the way, pushing for great formulas and pretty packaging -- plus, Flower doesn't spend money on advertising, saying they allocate more funds for product development. Barrymore also takes her role as a female entrepreneur in the beauty industry seriously. She told us at the launch event that she hopes her daughter, Olive, will someday take over the business.

Star product: Flower Zoom in Ultimate Mascara, $7.98

Just when I thought I couldn't love Miranda Kerr any more, here comes Kora Organics. All the products are certified organic and fair trade. It's also vegan, and free from sulfates, parabens, and synthetic fragrances. Clean would be an understatement.

Star product: Kora Organics 3-Step System, $139.95

To hear Jessica Alba talk about The Honest Company is to get a lesson in responsible, eco-conscious living. She's a walking, talking encyclopedia of green, natural, and sustainable ingredients and products. In addition to spearheading a company that produces dozens of affordable, green products, she wrote a book on the subject ("The Honest Life: Living Naturally and True to You").

Star product: The Honest Company Healing Balm, $12.95