4 ads in one page

Hi

lately i saw a lot site that have 4 google ads on one page...i thought google tos is only 3.do i missing something?

 

That site is breaking the rules. It's still only a maximum of 3 ad units per page.

 

You're not missing anything. 3 AdSense for content units maximum is correct.

 

I assume that the 3 ads are text/image ads-- but that search is not considered part of the 3???

 

No, the search does not count as "3 ad units". Referral buttons don't either.

 

that's impossible, if you have more than 3, google cancels out the bottom-most ad...

 

I know ads don't appear sometimes but does this always happen? How do they know its the lowest one?

I've seen a site with over 4 units before though.. so I'm not sure if they actually do "cancel" it out.

 

I've done it (purely by accident) - my site has many plugin spots. There were times when I had 4 Adsense ads on a page at once, and it always cancelled out the bottom banner or the bottom-most link ad near the footer of an article. It's pretty smart