Every day I am visiting a lot of websites and mostly the ordering pages; I can say that there are some webmasters that are totally ignore the customers they are serving.
For example, today I saw an ordering form which have the default quantity as zero ! Why would someone put the default quantity as zero? Believe me that I cannot answer to that question. Or maybe they really want to spend some money for a professional user testing service.
For all these king of webmasters, I have an advise: build the website and keep in mind that the website may be accessed by your grandmother (in this way, the usability is guaranteed)!