I was just searching for reviews on a popular Internet technology topic and happened upon a site with "Top 10" lists for various categories. On every page are three of the standard Adsense units (employing the off-the-shelf large, garish Verdana face):
300X250 (top right)
160X600 skyscraper (left column)
729X90 banner (below content)
But wait... there's more: Three more customized Adsense ad units (not Adlink units) are mixed in with the content. Each one displays the old "Google Ad" notice instead of "Ad Choices" and on each unit the text size was quite a bit smaller than the Title (link) size, suggesting a granular level of ad customization.
What's going on there? This doesn't look like a premium publisher with special privileges -- to the contrary, it looks pretty spammy. My best guess is that the content is framed and they've tweaked the unit and font sizes for the ads within the frame -- all in violation of Google's TOS, of course. Is this a good guess?
Oh, and of course the site's pages sit at or near the top of Google's organic search results. (That almost goes without saying.)