"The second aspect that drives satisfaction down is the increase in traffic," Freed said. "A large percentage of the visitors to your site are infrequent or first-time visitors ... and they are hard to please for multiple reasons. But the primary reason is they don't know their way around the site. They're not familiar with your shipping policies, and they're not familiar with your inventory policies, so the first-time or infrequent shopper will experience far less satisfaction than a frequent visitor to a site."

The lowest scoring sites among the top 40 were CompUSA.com, which had a score of 67, and Kmart and Sears, which were tied at 68, according to the survey. The sites with the biggest drop from the spring to the holiday season were ToysRUs.com, which showed a 10 percent drop; OldNavy.com, which had a 9 percent drop; and Sears.com and JCPenney.com, which saw 8 percent drops, according to the survey. Freed said 26 of the top 40 sites had scores that dropped more than 4 percent, which is considered a significant change.

Buy.com was the only company with a rising score. It went from a score of 71 last spring to 72 over the holidays; 1800Flowers.com, BananaRepublic.com and Chadwicks.com remained the same, according to Freed.

The following are other findings from the ACSI study:

- Shopping search engines are failing to fulfill their promise to top retailers. Consumers who come to a retail Web site through a shopping search engine are less likely to come back, buy something or recommend the site to a friend than if they come because of a company promotion or a referral.