Wall Street's bears are scratching their heads again. Amazon.com (NASDAQ:AMZN) has come through with another analyst-humbling quarter, with no slowdown in sight.

The e-tailer's quarterly highlights include:

  • Net sales rising 18% to $4.89 billion. A strengthening dollar against European currencies ate into the company's top line; on a constant dollar basis, net sales would have risen 25%.
  • Earnings climbed 24% to $177 million, or $0.41 a share. Analysts predicted a profit of just $0.31 a share.
  • North American sales climbed a sharp 21%. International sales were up 15% on a reported basis, but would have clocked in 28% higher without the foreign exchange fluctuations.
  • Free cash flow over the trailing 12 months soared 82% to $1.43 billion.

Valuation pundits will gravitate right to the company's bottom line, and shake their heads at what is now profitability of $1.56 a share over the past four quarters. Based on last night's close, can Amazon really be worth 52 times earnings?

Skeptics can also point to the company's lofty price-to-sales ratio of 1.8, given Amazon.com's $19.9 billion in net sales over the past year. That's clearly not a low number in retail, where Overstock.com (NASDAQ:OSTK), Wal-Mart (NYSE:WMT), and Best Buy (NYSE:BBY) all trade for less than 0.5 sales. On the other hand, Amazon is gradually transforming itself into a digital delivery company, where healthier margins dictate higher price-to-sales multiples.

However, the one metric that most bears review is the company's ability to generate free cash flow. $1.43 billion is a lot more than the $679 million the leading e-tailer scored over the same four quarters of the previous year. Amazon is actually trading at just 25 times trailing free cash flow. That may not make the stock a blue light special, but it does make the earnings multiple seem a bit less outlandish.

Bears who insist on sticking to the plain-vanilla earnings-based valuations -- a somewhat misleading metric, since it discounts the company's envious cash flow management model -- may also want to brush up on recent history. Amazon has now beaten Wall Street estimates for five consecutive quarters. The last two quarters have been blowouts, suggesting that analysts are seriously undershooting the company's prospects in this recession.

Amazon is growing where other retailers -- online or bricks-and-mortar alike -- are not. It's still not putting out hard numbers on the Kindle, but clearly, the e-tailer doesn't have a problem with its overall growth.

As other online merchants like Overstock.com, Drugstore.com (NASDAQ:DSCM), and Bluefly struggle to turn a profit, Amazon coasts. When real-world chains like Circuit City are closing down, and even discounters such as Target (NYSE:TGT) post monthly declines at the store level, Amazon has never been more appealing.

Attracting shoppers and bears alike? That doesn't sound like a bad combination, especially for contrarian bulls.  

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Amazon.com and Best Buy are Motley Fool Stock Advisor picks. Best Buy and Wal-Mart Stores are Motley Fool Inside Value picks. The Fool owns shares of Best Buy. Try any of our Foolish newsletter services free for 30 days.

Longtime Fool contributor Rick Munarriz has been shopping online for about as long as Amazon.com has been in business. He does not own shares in any of the stocks in this article. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.