Steve has posted a very challenging observation (citing someone else):
This articulates a subconscious reaction and really teaches us an important lesson.One interesting finding of these studies is that users really do judge a book by its cover… or rather, a website by its design. Elements such as layout, consistency, typography, color and style all affect how users perceive your website and what kind of image you project. Your website should project not only a good image but also the right one for your audience.
Other factors that influence credibility are: the quality of the website's content, amount of errors, rate of updates, ease of use and trustworthiness of authors.