Google Blogoscoped points to an article which discusses ugly websites and how having an ugly website can actually improve business.
I was developing a website design last week for a local educational institution – target audience of parents and students. I sat there trying to improve the design and to try and convey a more professional image and really wondered what the whole point was. A more professional website looks less friendly and besides, in the long run, content is king. In the end, I saved myself quite a bit of work 
The success of sites such as eBay and del.icio.us (which lacks much of a design) is probably due to the "ugly" design. eBay's design probably makes it feel more like a marketplace where you can get great deals rather than an upmarket department store such as M&S.
And perhaps that's why I still prefer the current Google design to the Google Redux and Slashdot's design to Digg.
Basically it's not about professionalism, but useability and trust.
Yes it’s an interesting thought that a more primitive design attracts more users, or more specifically, it makes users more comfortable interacting with the site. MySpace is the perfect example. Users aren’t afraid to play around designing their page because the MySpace template looks pretty terrible to begin with.