I (and I'm sure many other internet users) don't even take account of that stuff - I automatically hone into the content (typically, in a column somewhere near the left of the page) and ignore the ads to the sides.

Still, ads everywhere and a very busy content layout detracts from the usability of the site.

Clearly ( http://evernote.com/clearly/ ) does a really good job at scrubbing the page and changing the text to be more readable.