Investors are a fickle bunch.

Over the last few months, they dragged down Intuitive Surgical (NASDAQ:ISRG) more than 60% on worries that hospitals wouldn't be buying as many of its surgical robots. And then, when the company announced yesterday what investors already knew, they sent it down some more.

I mean really, was the lowered guidance such a big shock to anyone?

This recession has taken no prisoners. It's knocked down the usual suspects that you'd expect to show weakness -- cruise operator Carnival (NYSE:CCL), gamer Electronic Arts (NASDAQ:ERTS), and LCD-TV-screen glass maker (among other things) Corning (NYSE:GLW). But even fellow health-care companies -- medical tester Laboratory Corporation of America (NYSE:LH) and surgical implant maker Stryker (NYSE:SYK) come immediately to mind -- have recently warned about not making previous guidance.

And yet, here Intuitive Surgical sits, trading for 24 times free cash flow, which doesn't seem at all unreasonable given that it's expecting revenue growth of 15% this year. Earnings and free cash flow will presumably see a more substantial growth as most of that increase in revenue is expected to come from sales of higher-margin accessories; sales of systems are expected to remain flat.

And keep in mind that management has a way of being conservative with its guidance. This time last year, management was guiding for a 40% increase in revenues for 2008, and it looks like it'll come in at 46% ... even after the poor fourth quarter.

Investors with long-term horizons will likely see this downturn as a small blip on the general upward trend of the four-time Rule Breakers recommendation. What else would you expect from a company that can expect a 15% increase in revenue during bad times and 40%-60% growth during good times?

Find out why David Gardner and his team have recommended Intuitive Surgical four times for the Motley Fool Rule Breakers newsletter. Click here to see all of our latest discoveries with a free 30-day trial subscription.

Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool owns shares of Stryker. LabCorp and Electronic Arts are Motley Fool Stock Advisor picks. The Fool has a disclosure policy.