While browsing websites I just noticed the placement of the ads in the content. http://www.city-data.com/housing/houses-Maple-Valley-Washington.html I think if this one didn't violate any of Google Adsense TOS it's a very good ads placement don't you think?
He must be a premium publisher, but his site looks like spamy and I think he is using some script to display ads.
I am not sure you notice it or not, this site is a premier AdSense publisher. The ads display on this site is customized ads to fit into this site. Although this site is not unique and questionable, they republish data from census, has 1000s of Open directory listing, Google PR 8, and alexa ranking of 2900. This is perfect a MFA site but some reason Google love them so much. They ranked well for thousands of keywords.
A nice site with a lot of content about US cities - not sure where they got it all but it is a lot of detail about a lot of cities - no wonder google loves them...
The traffic from them must convert well to sales, and I guess adwords advertisers are paying well in their niche, so Google is happy with this kind of site, whatever you could say about it.
Design wise, the site is capturing no attention at all. Not mine at least. Information wise, however, it must have got a lot to say. Very rich content.