The market pushed shares of Energizer (NYSE:ENR) up over $10 this past month, a 20% increase from its previous trading range. Looking at the news, one can probably attribute the rise to the company's report of solid, though not spectacular, earnings for its quarter that ended Dec. 31.

Part of me wonders whether investors pulled the "buy" trigger too early. It seems as though they just looked at the first line in Energizer's press release that said the company earned $1.62 per diluted share vs. $1.32 last year, did the math, saw 23% earnings growth, and dove in.

But a closer look reveals that things weren't quite that rosy. For starters, the number of diluted shares outstanding decreased by 13% from the same quarter last year -- not a bad thing by itself, but it does make the earnings-per-share numbers higher. Some of the strong results were also the result of a weak dollar. When you back out those factors, you'll see that overall sales and income increased by only single digits.

So why are investors rewarding the company with a price-to-earnings ratio of 16? Look at the cash flow statement. Energizer produces scads of cash. This $5.4 billion company pumped out $267 million in free cash flow over the trailing 12 months, and although its balance sheet carries more than $1 billion in debt, I'd argue that it isn't much of a concern when the dough rolls in at such a fast pace.

Another thing investors must like is that Energizer is one of those very few companies that do one or two things and do them very well. Energizer sticks to what it knows, and it delivers consistently, so investors thus reward the stock with a premium P/E.

But let the buyer beware -- this could also mean the stock is priced for perfection. If the bunny stumbles, a fox like Procter & Gamble (NYSE:PG), which just bought Energizer competitor and Duracell parent Gillette (NYSE:G), might have its day.

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Lawrence Meyers doesn't own stock in any company mentioned in this article, but he does buy batteries, usually in bulk. Want to discuss the companies mentioned in this article? Check out the Fool's Energizer, Procter & Gamble, and Gillette discussion boards.