A whopping 65 percent of the 1,100 U.S. Internet users that were surveyed won't patronize a poorly designed site — even that of a favorite brand — and 30 percent reported that Web site design is more important than a great product. Even rock-bottom prices only persuaded 4 percent to shop on a poorly designed Web site.

What's worse is that nearly 30 percent stop buying from their favorite offline store if their online experience is poor.

Higher income levels appear to be less tolerant of poor site design. More than 70 percent of those earning $75,000+ per year say that they will not shop on a poorly designed site and may even discontinue offline purchases from a company with such a Web site, compared to 60 percent of those earning less than $50,000.

In addition, more than 75 percent of those between the ages of 25 and 34 say that usability is a very or extremely important factor in their online and offline purchase decisions, compared to 64 percent of those aged 45 to 54.

Genex's findings are in-line with a Jupiter Research (a unit of this site's corporate parent) study revealing that while customers are mainly driven by price, Web site ease of use is the most important factor in assessing sites to buy from online.

"Web site design is not about being pretty or slick — it's about the customer experience online and that means, ultimately, that its about sales," said David Glaze, vice president of creative, Genex. "As our survey shows, there are substantial financial consequences when a company does not pay enough attention to the usability and information design of its web site."

Usability and design play critical roles in site credibility, as Consumer Web Watch found through in-depth studies. Nearly half (46.1 percent) of survey participants ranked "design look" as the most important component when evaluating site credibility, followed by "design/structure."

The Consumer Web Watch report elaborates on the "design look" of a Web site with revealing comments from survey participants. Most notably, respondents said that a trustworthy site should have a polished, professional look, without being too slick.

"It looks like it's designed by a marketing team, and not by people who want to get you the information that you need," commented a survey participant during a test site evaluation.