Bad content, bad links, bad navigation, bad category pages... which is worst for business? In these examples, bad content takes the prize for costing the company the most money.
Every year, I see thousands of design mistakes in both user studies and everyday life. The curse of working with Don Norman is that half the elevator buttons I see make me angry: Why can't these guys do what Don told them to do 20 years ago?
Then again, Web designers don't do what I told them to do 13 years ago, so why am I surprised? Following is a modest harvest of design stupidities I've recently encountered.