Way more than 3 adsense ads on one page?

[webmastero]

I know that google doesn't allow the placement of more than three text/image ads on one page, but I saw quite a few websites (I can't give you any links though, but if needed I can do some research) which have 6-7 adsense units on their pages.

The fact that they do and they will eventually get banned is not really my concern, but how they do it - just out of curiosity. Because if I would try to place more than three text/image ads on a page, the extra ones would simply not show. So how come some websites can do it?

And, just to make sure everything gets it clear: I am certainly talking about Google AdSense ads only, and only text or image ad blocks.