Rat Dropping:
If you have a specific adserver or URL syntax you are curious about use Google to spy..
Example:
If I want to find all prosper202 servers I can do this:
allinurl: tracking202/redirect
and so on...
and so on...
then from there you can measure volume of the adserver , use alexa clickflow to see buying activity,
etc, etc...
or just do Whois lookups & build a huge affiliate base..
I know all a little vague but some will find useful esp. if you apply to 'stuff ' outside
of tracking202..
thanks Google!
-RATS
Been able to find a lot of LPs that way using site: thesite.com
BTW Even if you have your robots.txt or meta tag set to noindex, google still seems to index things if there is enough volume.
I think you can ask to have those results removed via google webmaster tools, but not sure the exact process on that.
To what end?
- another good tip on a similar note is to customize your adserver not to show Ads to certain IP ranges (..like Networks & Proxy Services )
- the key is finding URL styles that are worth investigating....
- you can also PPV pop on this type of stuff (but be very careful you do not breach legalities )
RA
RATS droppin' bombs
Lot of time you can do IP Neighborhood lookups and find all the domains owned by someone.
DROP THE BOMB!
Excellent tip - thanks Rat man.
Sneaky sneaky stuff shared in here 
If you think that's cool then you will prob go crazy over the tool a dev friend of mine is working on. You can basically search the source code of html, css, js files for anything.
* Pixels
* Analytics ids
* Affiliate ids
* Links
* meta tag contents
* header tag contents
* whatever you can think of
I remember this was shared a view years ago and its one of the few things i kept in my little affiliatemarketingspecialties.txt file.
^^ That's next level spying, almost scary the point its getting to 
It's going to be hard to keep campaigns running longer then a week lol
here is a free way to do it; https://search.nerdydata.com/