Is this some kind of Murphy's law? Maybe if I want to hire a very good programming ninja I should check out his website as in "Show my your website and I will tell how good you are"

EDIT:
Go stackoverflow top users tab and you will see

Because design is a specialization, just like programming: not everyone can do it. It takes years of training and experience to know how to recognize and implement good design.

Most people are not true polymaths, and either do not have the time, inclination, or ability to master two specializations.

Beyond that, most people don't have the resources to hire a professional designer to do their website. So, add that to the general programmer inclination to write one's own version of a website instead of using off-the-shelf tools, and you have a recipe for a lot of programmers creating websites that don't really look all that great.
