Back in my hedge fund days, we did a TON of work on U.S. egg prices. This was back in 2003-2004 in the throes of the Atkins craze. Pasta companies, companies with a lot of exposure to grain, and anything anti-Atkins was taking a hit. Even the great, Weight Watchers (NYSE: WTW), with just a great business model and brand, was getting whacked. It looked like Atkins, and its seemingly lethal blend of high fat and high protein, was going to stay.

We decided to play this trend by purchasing Cal-Maine Foods (NYSE: CALM), a huge distributor of eggs to the likes of Wal-Mart (NYSE: WMT) and other huge grocery outfits. Based in Jackson, Mississippi, and run by an effervescent CEO, Fred Adams, Cal-Maine rode record egg prices those couple of years. In 2003 alone, the stock was up almost 1000%.

What Mr. Adams told us then was that although Atkins was helping to increase demand for eggs, the egg itself was making a comeback. Once shunned as solely a cholesterol-delivery device, the egg is back in fashion and recognized for its overall health benefits.

Cage-free eggs are the latest forefront in the constant PR campaign of many leading retail companies to be seen as the humanest, the most animal-friendly, the most vigilant about the health of its products. As indication of the bigness of this particular buzz-phrase, several weeks ago, Burger King Holdings Inc. (NYSE: BKC) announced a switch to both cage-free eggs and pork products. So important is the issue that when Portland, Oregon fast food chain Burgerville broadcast their own switch to cage-free, local media cried, when will Starbucks Corporation (NASDAQ: SBUX) switch all the eggs in its products (including its popular breakfast sandwiches) to cage-free?

The answer could be far more muddled than (for instance) the coffee giant's recent changeover to hormone-free milk or trans-fat-free baked goods. Here's the thing: it's not necessarily assured that cage-free eggs are the be-all and end-all of chicken humanity. And the costs go far beyond a little extra space.

This is not to say that I disagree with cage-free eggs, quite the contrary: I recently began raising chickens (Bella, Mathilda and Twitter are now six weeks old, and were recently joined by baby "sisters" Gilda and Genevieve) much because of the considerable health and taste benefits of cage-free eggs. Ideally (and in my own backyard), chickens who are not confined to cages get more exercise and a more balanced diet, including greens (they love blackberry and dandelion leaves). The eggs are therefore packed with good vitamins, making the yolks more orange and the shells sturdier -- whether brown, white, or pinkish.

But not all cage-free chickens are raised equally.