The diversity of the web sites reflects another positive quality of your designer, and that is the fact that they really communicate well with their clients. They get hired by a business, and they make every possible effort to find out exactly what the business stands for, and what they wish to accomplish with their web site. This becomes obvious when you see the final product. If possible, you should find feedback of the particular agency, and see if their previous clients mention anything about their cooperativeness, or their ability to work with the company to create a better site.
All of these qualities point to the overall ability of a web design agency to create a web site that satisfies the customers desires, as well as sell whatever product or service the company is offering. So if you are starting a web design agency, do everything you can to strive towards these ideals. And if you are looking for a web design agency to make a web site for your company, be sure to consider all of these factors when considering each prospect.