Cola and snack giant PepsiCo (NYSE: PEP) may be a great buy right now -- in fact, I recently offered three reasons detailing why that's the case.

But if you haven't found any blemishes on an investment you're looking at, then you're just not looking hard enough. While there are certainly good reasons to be a PepsiCo buyer right now, there are also reasons to be wary of the stock.

Let's look at three of those bearish issues.

1. Recent performance
The bottom line is that in recent years, PepsiCo simply hasn't delivered in a big way for investors.

Sure, we could say that for the five years ending in 2011 that the company's revenue jumped 89% -- or about 14% per year -- but much of that growth was due to the acquisition of Pepsi's bottlers. If we skip down the income statement to the bottom line, it's easy to see that far less has happened there, where it really matters for investors. Earnings per share were up just 21% over the same period, for a much weaker 4% compounded annual growth rate.

This might be easier to shrug off if we saw similar sluggishness across the sector. Chief beverage rival Coca-Cola (NYSE: KO) though, managed to boost its EPS by 71% over the same stretch, notching an enviable 11% growth rate. Dr Pepper Snapple also managed to top PepsiCo, growing its earnings more than 6% per year over those five years.

Of course, it's important to remember that about half of PepsiCo's business comes from food and snacks. When we look at comparables on that side of the business, it's not quite as bad. Kraft (NYSE: KFT) managed only total growth of 16%, while Hershey managed only a slightly better 17%. These companies have had to wrestle with getting squeezed from both sides -- the recession affecting demand while rising commodity prices raised costs.

Can we excuse PepsiCo's lackluster recent financials? It's debatable. If it's able to turn things around and start delivering more attractive growth, then all could probably be forgiven. But at least as of the first quarter, it doesn't look promising that a turnaround like that is imminent. For the quarter, "core" earnings per share were down 7% and management still expects a 5% full-year decline in core EPS.

2. Opportunity cost
If you sink $1,000 into PepsiCo stock, that's $1,000 that you can't invest in Coke, Dr Pepper, or any other stock -- or any other asset, for that matter. Perhaps that sounds obvious, but investors do need to keep an eye on the opportunity cost of the investment they're making.

With PepsiCo you're getting a solid, high-quality company with great brands and -- in my view, at least -- very solid leadership. What you're not getting is a stock like Banco Santander (NYSE: SAN) that's so beaten down that good news -- say, a string of progress reports on mending the eurozone's debt crisis -- could send it soaring. You're also not getting a Tesla Motors (Nasdaq: TSLA), a company operating at the bleeding edge of its industry and set up for huge long-term gains if its Model S turns out to be a big success.

As a $110 billion company that pays a 3.1% dividend and owns one of the most recognized brands on the planet, PepsiCo offers a solid case as a steady performer and a good, core holding. But if a quick home run is what you're after, you're bound to be disappointed.

And, with a nod back to No. 1, if PepsiCo doesn't get its ship moving again, the opportunity cost could be high even when compared with large, similarly situated competitors like Coke or Kraft.

3. A big swing and a miss
I like to make healthy food choices, so I appreciate the efforts PepsiCo is making to try to deliver healthier drinks and quick-snack options for its customers. Granted, we'll probably never hear PepsiCo in the same breath as Whole Foods (Frito-Lay brand kale?), but there's something to be said for offering Naked Juice in favor of Pepsi, Baked Lays over Doritos, or Quaker Oats versus Cap'n Crunch.

But despite the dire health consequences, Americans have historically been amazingly stubborn about changing their eating habits. As a result, efforts focused on better-for-you products could backfire for PepsiCo, as the time and money spent could be more profitably deployed in its traditional snack and soda properties. Any loss of focus on the less-healthy but much-loved products could also allow competitors like Coke, Kraft, or Dr Pepper to gain ground.

I have my fingers crossed that the effort works out -- for the company's sake and the health of the country -- but the push is a risk.

Drinking it up
I have these risks front and center on my radar, but even after accounting for them, I think PepsiCo is a good bet. I've backed this up by rating the stock an outperformer in my Motley Fool CAPS portfolio, and I've bought it for my personal portfolio.

But perhaps you've been turned off PepsiCo by the risks I've outlined. In that case, you may want to check out three other impressive dividend payers -- including beverage king Coke -- that my fellow Fools think investors need. To read more, download a free copy of The Motley Fool's special report.