So here are a couple of thoughts
1. Are these sites bringing in more traffic on your PPC campaign?
2. Is the quality of the traffic that they are bringing of the right standard?
Some of the other sites are a bit less prominent in their list of hits. May be it's the industry we are in, but some of the sites discussed in WW don't even appear on our logs period, which is strange, as we automatically optimise for Inktomi and the major engines that seem to be powering PPC affiliates.
It also depends on which PPC Providers you are using for your particular PPC campaign.
This could lead to some interesting options for optimising PPC campaigns.
The thrust of this thread is whether the PPC affiliate sites are giving as good an ROI as the 'traditional' PPC sites such as Google, MSN, Altavista, AOL etc.
I wouldn't therefore make it part of a long-term strategy!
I think there is a measurable difference between a PPC partner that has content of their own and uses PPC associations as an additional revenue stream compared to Cobranded PPC sites with no real content of their own. I think therefore that future filters designed to stop the later would have to find someway of still appreciating the former.
Afterall if you operate your own directory with say a sponsored links product your pages are still unique and worthy of indexing. However if your site is effectively a replica of PPC content found easily elsewhere then the value of indexing such pages is not as high.
Should one search engine direct users to the pages of another? Well if those pages are new and refreshing and offer a different slant on the original query string then maybe. I think the real goal though must be to avoid mass content duplication, thats not that helpful in a search.
Talking from the point of view of a searcher rather than a SEO - It annoys me something cronic when I search for baby stuff, I want a result that I can click on that takes me to that particular item.
What I don't want is a page that brings up links to PPC links of other sites, most of these are then shopping comparison sites, rather than individual items.
It sometimes taking me 3 pages before I even get to a site that I can buy what I want.
Remember that a lot of webmasters had sites die in the Florida update and many previous Google updates, and PPC is the only way that they can bring in steady business. For them, if they can't get natural SEO traffic, such PPC affiliate sites are great news; if the traffic quality if good.
edited spelling!