Other ad-network members seeing rankings decline?

[geoinct]

I’m working with a new client. They were reaching page one on Google for many important phrases. However in the last 2 weeks they have plummeted.

I’m starting by going through the site looking for anything they may be doing that could get their incoming links devalued, etc

They are using a well know ad-network. Here’s the way they are using it on the site. I’m not sure if this is typical. They include text links to other member’s sites at the bottom of each web page. To me that’s very spammy and could be causing problems.

Have anyone else who is using an ad-network like this seen a dramatic drop in rankings lately?

[tedster]

I agree with you that it sounds very spammy, unless there is rel="nofollow" attribute on those links. Basically it comes off like an old school link network -- just the kind of thing we've heard Matt Cutts warn about.

Is that all the "advertising" that this ad-network does, or is it in addition to something else, such as banner ads, interstitials or text-link ads?