A very interesting thread is brewing over at Digitalpoint Titled The advantage of "ugly" over "pretty". The thread seems to be focused directly on the CTR of AdSense on ugly sites vs pretty websites.
User Troutnut posts:
It's too easy to set up a "pretty" site. Just download one of the thousands of free forum scripts, CMSes, etc, and pick from the thousands of themes available, and you're all set. Many of them have very pretty layouts with nice subtle touches of borders, bevels, gradients, rounded edges, yadda yadda yadda.
The result is that there are lots of these cookie-cutter pretty sites on the web with little to no content. Somebody puts WhateverNuke on autopilot, adds a few crappy articles, throws on some ads, and forgets about it. The menu is packed with links to feature-rich, well-designed sections with "No widgets have been added yet" where the content's supposed to be. The web is cluttered with pretty, hollow skeletons of websites.
I think maybe web users are becoming conditoned to associate stylish designs with these hollow skeletons. And if that's true, one way to a successful design may be to create a home-made feel. It isn't that they're ugly that helps; it's that they look like somebody took some time to personally build them from scratch, and that means it's likely they put a similar amount of care into the content. A custom site has something worth saying.
Some of the more interesting posts in the thread-
User Sbabb posts:
Is his theory that an ugly site makes people want to click away immediately, so they click on his ads to leave?