Acting on panic never helps investors, but it's still a good idea to question why you're really buying individual investments.

Consider robot maker iRobot (Nasdaq: IRBT). Though the company is gushing with optimism, you'll find a few of the 1,119 Motley Fool CAPS members weighing in on the company offering reasons to be bearish.

Here at The Motley Fool, we like to consider both the good and bad sides of an investment. In this article I'm highlighting three of the main bearish arguments on iRobot today, but be sure to read the bullish side as well. Then weigh in with your own comments below or rate iRobot in CAPS.

1. One heavy customer
While defense contractors such as Lockheed Martin (NYSE: LMT), Boeing (NYSE: BA), and General Dynamics (NYSE: GD) all face the threat of a shrinking defense budget, each has diverse product lines and customers. But with 37% of iRobot's revenue coming directly or indirectly from the U.S. government last year, there's some risk that the loss of government contracts would have a dramatic effect on its business.              

2. Consumer spending
Consumer robots make up a big portion of iRobot's revenue, but despite an increase in sales, some investors aren't convinced the streak can continue at the same pace. Retailers that sell Roombas, like Sears Holdings (Nasdaq: SHLD) and Best Buy (NYSE: BBY), posted weaker-than-expected sales in their most recent quarters, and some investors don't expect pricey robot vacuums to be a must-have item for consumers in the U.S. and regions, like Europe, that remain locked in economic doldrums.

3. Vacuum competition
Although Roomba has held the top robot vacuum spot for a while, new entrants to the market aim to get a piece of the action. While Honda's (NYSE: HMC) Asimo robot is a long way from having a place in many homes, LG Electronics, Neato, and Samsung have all introduced robot vacuums that can be a direct threat to the Roomba and put a damper on iRobot's outsized revenue growth abroad.

To see details of what CAPS members are saying now about iRobot, just click on over to Motley Fool CAPS and have a look, or add your thoughts in the comments box below.

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Fool contributor Dave Mock now has three more reasons to eat Oreo cookies for breakfast. He owns no shares of companies mentioned here. Best Buy and General Dynamics are Inside Value recommendations. iRobot is a Rule Breakers selection. Best Buy is a Stock Advisor pick. Motley Fool Options has recommended a bull call spread position on Best Buy. The Fool owns shares of Best Buy. The Fool's disclosure policy spent five years on a chain gang, but still claims to have been framed by The Man.