Consumer stocks are now as risky as they've ever been. Unemployment's historically high, consumers are spooked, and subpar earnings abound, as companies pay the price for lost competitive advantage or fiscal irresponsibility. But tough times can offer investors the best chance to buy stocks. 

Even if stock prices are low, investors still need to be careful. Many companies simply won't survive the recession in their current form. And even if you believe an investment's a strong buy, it's always Foolish to play devil's advocate, probing for its potential weak spots. To keep you and your portfolio ready for anything, I've highlighted two reasons to turn your back on global tobacco giant Philip Morris International (NYSE: PM).

Ashes to ashes?
In a companion article, I suggested that Big Phil's strong brands and attractive dividend made shares a smoking buy. Here, I explain why shares could fall as company growth is eventually snuffed out.

1. Taxes axe consumption
Sure, the demand-killing effects of cigarette taxestend to be associated with former Philip Morris parent company Altria (NYSE: MO), along with U.S.-focused tobacco names that include Lorillard (NYSE: LO), Reynolds American (NYSE: RAI), and Vector Group (NYSE: VGR). Higher internationaltaxes, however, are also beginning to pose a threat to consumers' high-end cravings.

My colleague Colleen Paulson already mentioned Philip Morris' third-quarter volume decline. Specifically, the company attributed "nearly two-thirds" of its organic volume weakness to three countries: Spain, Pakistan, and Ukraine. Not coincidentally, all of these regions recently raised excise taxes, prompting management to lift prices. In the case of Ukraine, management hiked prices 22% to 50% in response to taxes that more than quadrupled from January 2008 to May 2009.

In addition, Brazil boosted excise taxes 20% earlier in the year. That could help explain why Latin American volumes sunk 3.8% in the third quarter, excluding acquisitions. Finally, management cited Mexico's volume softness as "primarily reflecting the impact of tax-driven price increases in January and December 2008."

It's encouraging that adverse tax developments haven't been reported in key growth markets of China, India, Bangladesh, and Vietnam. Moreover, in the near term, management is "optimistic" that most governments will act rationally. That said, you don't have to be addled by nicotine withdrawal to wonder whether the situation in parts of Europe and in Brazil is the beginning of the end.

2. Room to fall
Valuation is the second reason that investors should consider going on the patch program. Shares of Philip Morris International have risen roughly 50% since the March lows. Of course, that alone doesn't mean that the stock has become overvalued. Yet shares trade at a forward P/E of 12.9, substantially above the 9.8 and 10.1 numbers for Altria and Reynolds American, respectively. And, I add, above the 12.1 forward P/E the market's assigned to globetrotting competitor British American Tobacco (NYSE: BTI). Continued...