Sure, we all feel like geniuses now, right? We stuck it out -- "it" being the worst economic crisis since the Great Depression -- and have now enjoyed a rocket ride with fat and happy double-digit gains over the past two months alone.

There's surely more to come, right? Right?!

Survey says!
Who knows? We Fools pride ourselves not on making market calls, which is a great way to get slapped silly by the market's invisible hand, but rather on our fundamental focus: Is a company's market share likely to shrink or grow? Has its management team delivered the goods over the long haul while deftly navigating up markets and down? And in terms of valuation, does the firm's stock look like a blue-light special or a high-end luxury item?

In my experience, it's that last element -- valuation -- that's often the toughest taco to crack. Some companies never look cheap, after all, while others that appear to be bargains may turn out to be value traps instead. Still, in general terms, one thing remains true: When a company sports moon-shot multiples, there's little opportunity to cushion the blow when the overall market hits the skids or when the company itself blows up.

The higher they fly, the harder they fall
Take, for example, Research In Motion (Nasdaq: RIMM) and Google (Nasdaq: GOOG). The former has more than doubled over the past three months, while the latter has racked up a gain of nearly 40% year to date. Yet sneaking a peek at this illustration of recent history should be instructive for folks who may currently own either company's shares, as well as Fools who may be considering a purchase.

Yikes, that's a long way down. But, to be fair, that kind of rearview analysis always begs the question of whether investors could have -- or should have -- seen writing on the wall. My take: Perhaps not, but if they'd tuned into each firm's valuation, savvy investors might have gotten an early warning. Shortly before its slide began, after all, Research In Motion traded at a level that priced in more than 60 times the previous year's earnings. Google, meanwhile, sported a P/E in the 50s back when we were celebrating New Year's 2008.

Bottom line: Be afraid of these stocks, be very afraid. When an all-but-inevitable market pullback arrives, they are sitting -- or in this case flying -- ducks.

Good company, lousy investment
Genzyme (Nasdaq: GENZ) and Teva Pharmaceutical (Nasdaq: TEVA) look priced to fall just now, too.

Make no mistake. Like Google and RIMM, these are fine businesses; their stocks are just not finely priced. Indeed, their P/Es currently sail past both the broader market's and each company's respective industry average. From my cheapskate's perspective, that makes the downside risk of dreaded "multiple compression" just too great, particularly when long-haul overachievers like Chevron (NYSE: CVX) and ConocoPhillips (NYSE: COP) are still available at bargain-basement prices, comparatively speaking. Continued...