Last summer, the world believed pure e-tailing would win the war for customers; eyeballs and clickthroughs measured success; slick websites mattered and first movers would have a huge advantage online. This summer, with much-visited, high-glitz sites of early movers like Boo.com filed for bankruptcy; gloss.com sold to incumbent Estee Lauder; and Super Bowl advertisers like Healtheon WebMD and Pets.com hemorrhaging cash, we can barely contemplate the full costs of e-tailing and shakeout that's underway.

So is it time for the smart rats to leave a sinking ship? Is all electronic retailing going under? A recent Bain study suggests the smartest rats will reserve judgment until they've checked out four signs of seaworthiness in their online ventures. These include the business basics of: abilities to sell products through multiple channels; using the Internet to improve the cost and means by which products move from suppliers, in-house and on to customers; creating functions on their sites that engage customers and convert browsers to buyers; and offering unique products or services relative to established mass competitors.

The sustainability of an e-retail business depends on how well it plays along these dimensions. If you are a pure e-tailer, using an existing value chain and competing broadly, without unique applications, against established mass-market players, you have an unsustainable business model. A number of foundering online retailers, like Drkoop.com, are in this box. On the other hand, the companies more likely to meet success have differentiated on two, three or all dimensions.

To prove this point broadly, we ran a model taking all the public business-to-consumer companies and assigning them scores ranging from 1 to 10 along all four dimensions. Schwab, for example, would score highly on the first dimension—its ability to integrate its offer across all channels. While 80% of Schwab clients' trades have moved online; 70% of Schwab's new assets come under management through its branch locations. E-Toys, on the other hand, would score low as a pure e-tailer selling standard toys via a single channel.

On the second dimension, called "value chain," a company like Buy.com, would score below average, as it essentially serves as an online "front" for an existing supply chain. But CD MP3 would score well above average because it replaces a physical product with an electronic download. So would FogDog, which has created a new and improved value chain in sporting goods that provides unparalleled product breadth and depth by seamlessly integrating across manufacturers and distributors of all tiers.

On the third dimension, we assessed whether a web site is purely a collection of static web pages, or has unique applications that create stickiness and conversions to sales. A high-scorer on this dimension would be Amazon.com, with its well-known—yet unique—application that creates book recommendations to customers based on their purchase histories. Travelocity, too, would score highly: its rapid-response applications keep customers online and loyal. Airline ticket shoppers at Travelocity wait only 35 seconds for a reply, versus a full minute on competitor Expedia. Priceline's applications, too, would garner high ratings. The discount retailer's search engines create a reverse auction that allows shoppers to set their own, individual prices for purchasing travel tickets or reserving lodgings. Then the web site entertains bidders with virtual slot machines as they wait for a match.

Finally, we scored companies on their basis of competition. Is the e-business merely replicating an existing mass play or has it established a defensible niche that could constitute a new product or service? Here, high scorers would include Reflect.com, with its personalized and customized beauty products, or Smarterkids, which aggregates educational toys, not easily available to anyone, anywhere.

The upshot: B2C e-businesses that scored highly on these four dimensions—all business fundamentals—tended to have higher market multiples. Indeed, the top quartile's average market value to sales multiple ratio (20) was more than double the bottom quartile's (8). Ultimately, these businesses stand the best chance of scoring on the new metric of success: profitability.

The bottom line: a rising tide may lift all boats, but not all boats have the same ability to weather turbulence and navigate shoals. There is a way to start thinking about successful and sustainable B2C e-commerce models. Evaluate your vessel before you prematurely jump ship—or unwittingly drown.