We have a long-standing joke here at Fool HQ, one that has been going around for years now -- Starbucks' (NASDAQ:SBUX) numbers are always so impressive that it's gotten, well, kind of boring. Well, today investors got a little taste of change, and let's just say they didn't find it amusing. The coffee purveyor's shares fell as much as 14% at one point today on the company's earnings report.

Starbucks' third-quarter net income may have risen 16% to $145.5 million, or $0.18 per share, but earnings included a penny per share gain from a one-time income tax benefit, and analysts had expected earnings of $0.17 per share. Sales increased 23% to $1.96 billion, and same-store sales for the quarter increased 6%. Operating margin dropped to 10.9%, which is worthwhile to note since it has come in between 11.8% and 12.4% in recent memory; Starbucks said the major reason for the drop was expenses connected to stock-based compensation. Gross margin was 59.0% and net margin was 7.4%, both of which dipped from previous quarters (to compare these to the figures on a sequential and year-over-year basis, please see Rich Smith's chart in his Foolish Forecast).

Apparently investors are mostly bent out of shape because Starbucks reported something we haven't seen in a very, very long time: same-store sales for one month at the low end of the company's projected 3% to 7% increases. In July, Starbucks' same-store sales increased a mere 4%, and in what seems like a rather odd turn of events, the company attributed weakness to high demand for frozen beverages, which it said slowed down the efficiency of morning queues (and theoretically caused some customers to skip their Starbucks break).

Judging by the stocks' plunge today, maybe people aren't buying that excuse, and of course this is exacerbated by all the recent angst about the health of consumer spending. In addition, I saw a news report yesterday that implied that some people took Whole Foods' (NASDAQ:WFMI) recent earnings report -- which some considered "weak" -- to mean that affluent consumers are paring down, and associating that with Starbucks as well.

Although I do find the Frappuccino excuse a little strange, I think people ought to remember that a comps number like this was inevitable, given that Starbucks has been excelling against tough comparisons for years now. (That's what got a little bit boring in previous years. Starbucks' same-store sales increased 7% last July, 10% in July 2004, and 8% in July 2003, for example.)

Furthermore, I'm not convinced a consumer spending slowdown is certain to hurt Starbucks; it did remarkably well during the last recession, which always made me think that people are more willing to spare a few dollars on a cup of coffee as an affordable luxury, even while they're paring down higher priced treats like expensive dinners out. Starbucks is the leader in the industry, despite having competitors in Peet's (NASDAQ:PEET) and Caribou (NASDAQ:CBOU).

Today might very well represent a great opportunity to take a stake in Starbucks, considering that this stock generally trades at premium prices (granted, minor disappointments like today's do tend to set the stock back at times, as is the case with many such stocks). David Gardner recommended Starbucks to Motley Fool Stock Advisor subscribers back in March, in part because of its growth opportunities overseas. Indeed, not only did the company say it plans to open 2,400 stores next year (including a whopping 1,000 here in the U.S.), it's talking about its opportunities in large, attractive markets like China, Brazil, India, and Russia. Although there are a few elements that might give us pause, there's good reason to believe investors are overreacting by a long shot today.

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Alyce Lomax owns shares of Starbucks but of none of the other companies mentioned. The Fool has a disclosure policy.