Detecting whether banner ads pass link juice

Question

I wanted to determine the relative SEO value of the advertising links passed by this website: http://www.garden.org/

On the right side you'll notice several advertising banners that, when clicked, redirect you to the appropriate website. If you inspect any of these banners you'll notice that while the a href has a bunch of the usual ad garbage in the URL, there's nothing in there that's nofollow.
Why is it that when I check out any of these site's backlink profiles (via opensiteexplorer) that I can't find any trace of backlinks from garden.org?

Very new to SEO, please be kind. :)

Answer 1

Hi NotMuchOfAProgrammer,

It's not a real backlink since the Javascript is injecting the URL after the page has been loaded. If you disable javascript you will see:

<noscript>
    <a href="http://ads.garden.org/www/delivery/ck.php?n=aa4a0d78&amp;cb=INSERT_RANDOM_NUMBER_HERE" target="_blank">
        <img src="http://ads.garden.org/www/delivery/avw.php?zoneid=104&amp;cb=INSERT_RANDOM_NUMBER_HERE&amp;n=aa4a0d78" border="0" alt="">
    </a>
</noscript>

Which has no back link ;)

Most sites that you buy space for advertising will use a Javascript, Redirect, Flash Ad or a simple nofollow. Good sites do this because selling of links is against Googles policy and they actually downrank their in rankings and PR if they are caught doing so.