The turmoil in the markets makes it too easy to justify selling any stock these days. Yet, while panic never helps investors, it's still a good idea to play devil's advocate with investments.

Consider online retail king Amazon.com (NASDAQ:AMZN). Though the company continues to impress, you'll find that more than a few of the 4,267 Motley Fool CAPS members weighing in on it offer reasons to be bearish.

Here at the Fool, we like to consider both the good and the bad sides of an investment, so I'm highlighting three of the main bearish arguments on Amazon today. Be sure to read the bullish side as well, and then weigh in with your own comments below or rate Amazon in CAPS.                            

1. Overvalued
I know, I know. Who hasn't heard that Amazon's shares are overvalued? They've recently reached their highest prices ever on news of a strong quarter, and many investors are asking -- is it worth it? Amazon's valuation now dwarfs those of big-box retail competitors such as Costco (NYSE:COST) and Target (NYSE:TGT), and some CAPS members say that the company's wild growth potential just doesn't justify the current price.  

2. Price competition
Amazon is already familiar with competitors like Wal-Mart (NYSE:WMT) trying to lure away its business, but competition is expected to increase. In addition to competition for the Kindle reader from Sony and Barnes & Noble (NYSE:BKS), Amazon has to contend with eBay (NASDAQ:EBAY) and others, which could lead to lower prices chipping away at margins. It's a threat that has been cited for years, but one that should still be considered.

3. State of the economy
Although many investors think Amazon is a much stronger business than others like Overstock.com (NASDAQ:OSTK), many are still concerned about the economy's effects on consumer spending in the future. The company may get a boost from holiday sales, but with continuing weak economic data, many CAPS members expect more economic pain and prefer to sit on the sidelines.

Of course, Amazon has thrived despite past obstacles. But the question of its future viability is why CAPS is such a great resource. To see details of what CAPS members are saying now about Amazon, just click on over to Motley Fool CAPS and have a look -- or add your own thoughts to this story in the comments box below.

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Fool contributor Dave Mock is three for three in beating his son at chess, but he knows his days of dominance are limited. He doesn't own shares of companies mentioned here. Amazon, Costco, and eBay are Stock Advisor selections. Costco and Wal-Mart Stores are Inside Value picks. The Fool owns shares of Costco. This year, the Fool's disclosure policy isn't waiting for all the guests to arrive and will crack open the eggnog when it darn well feels like it.