Investors are doing themselves a major disservice if they simply stop at the top line. I'm not talking about income statements or even Dear John letters. I am referring to headlines that often bait you with unrequited love.

"Amazon.com's 12th Holiday Season is the Best Ever," reads this morning's headline out of the country's top online retailer. But all that glitters at Amazon.com (NASDAQ:AMZN) isn't gold.

For starters, of course it's going to be a record holiday season. There are more folks online. More importantly for merchants like Amazon, there are also more folks trusting the Internet with their credit cards as they stock up their virtual shopping carts. And let's be frank for a moment: Even the sometimes stodgy offline chains also post perpetual improvement, because that's the nature of inflation and favorable holiday spending trends.

What investors need to do is dig deeper into the gravy, and that usually means more than just reading further into a release.

It's not the growth, but the rate of that growth
When you tag something as "the best ever," it helps to flesh out the level of greatness. After all, this was the headline that Amazon rolled with after last year's season:

"Amazon.com Customers Order Over 108 Million Items Worldwide During 11th Holiday Season"

So how many more items did Amazon ring up this time around? This morning's release is suspiciously absent on that front. The only real "apples to apples" numbers we get are the tallies from the biggest day for orders and shipping fulfillment.

By now, we already know that Amazon's biggest selling day isn't the offline staple of Black Friday (the day after Thanksgiving), or even the inappropriately labeled Cyber Monday that takes place three days later. The big day for e-tail is the second Monday of December. That is when folks arrive at work, conclude that they are nowhere near finished with their holiday shopping, and spend company time on sites like Amazon and Overstock.com (NASDAQ:OSTK) to make sure that they place their last-minute orders with ample time for holiday delivery.

So how did Amazon.com do on Dec. 11, 2006 -- the real Cyber Monday? According to today's release, Amazon orders "exceeded 4 million items" on that day. A year earlier, on Monday, Dec. 12, 2005? The company's Delight-o-Meter rang up more than 3.6 million items. So all we know is that the number of things sold on that day this year was at least 11% greater than a year ago. Could it have been a lot more than that? It's unlikely. A vague statement like "exceeded 4 million," after the company posted a more concrete number a year earlier, would lead investors to assume that even 4.1 million may be an optimistic stretch. Last year's release wasn't worded as "orders that exceeded 3.5 million" when the company had the rounder 3.6 million figure to toss out.

The growth appears more encouraging on the fulfillment side. On its busiest day, Amazon shipped out 3.4 million units. That is a healthy 26% gain over last year's record, when the company fulfilled 2.7 million items. However, that is an imperfect gauge, as several factors like weekend backlogs and inventory timing issues come into play.

Sure, jumping to conclusions based on the number of units is also iffy, since we don't know average selling prices on those items. But it is a better indicator, since it reflects more on the consumer than on Amazon's ability to ship stuff out.

Does this mean that the company's fourth-quarter sales growth will clock in lower than last year's 22% rate (before unfavorable currency exchange rates knocked net sales growth down to 17%)? It could certainly happen. We have incomplete data, of course, yet Wall Street is looking for sales to grow from $2.98 billion during last year's seasonally spiked quarter to $3.77 million this time around. That implies a rather ambitious 26.5% in top-line growth. If I had to wager on either side of the net-sales fence, I would guess that Amazon misses that mark (even if it is able to make up ground on the way to a more market-appeasing bottom-line showing).

An Xbox 360 in every pot?
Another item in the company's press release that deserves some more bulb wattage is the claim that it "wrapped up its first ever Amazon Customers Vote promotion, where 1,000 Xbox 360s were sold in 29 seconds."

Did you miss something? Was Microsoft's (NASDAQ:MSFT) gaming console really that hot an item? In reality, it was, as parents turned to the Xbox system given the lack of availability of the newer PS3 and Wii systems. However, nowhere in the press release does Amazon indicate that it sold those particular units in a hyped promotion at $100 a pop, or 75% off the system's retail price.

More to the point, that promotion itself was buggy at best. Once its discussion boards were filled with irate shoppers that missed out on the limited deals, Amazon bumped its second weekly promotion before ultimately going with a lottery-based system for customers to score the bargain-priced deals.

So, yes, it is only a press release. Yet like so many words that are strung together these days, there is a lot more to it than meets the eye.

Amazon has been recommended to Motley Fool Stock Advisor newsletter subscribers. Microsoft is an Inside Value stock selection. Overstock is a former Rule Breakers pick.

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