What is the SEO opinion of interstitial ads?

[Matty B]

Does anyone have any facts or guidance on the SEO impact of using interstitial ads? They appear on a number of "big budget" sites like top-tier newspapers, magazines and video sites yet my guess is that Google and others would take a less favorable view of small sites using these ads. They are quite admittedly annoying, but can be profitable and beneficial in some situations.

Does anyone have any first-hand experience working with these ads and the results (good, bad or non-existent) from the various search engines?

[Free the Rabbits]

Hmmmm,
I have used interstitial ads on a couple of my sites from a number of providers (adsense et al).

From my experience

Full Page Ads
In my honest opinion, they do not provide a consistent income as they only serve to annoy the web users. I tried and tested and would never use full page ads again (unless your only focus is income but this will come at the cost of users and traffic).

in text ads
these are somewhat less annoying for users - when using the in text ads I found that the revenue was pretty pump.

In my expereince, fixed ads work best, I use Google, Tradedoubler and Commision Junction. Google is always the highest performa but the other 2 can bring bigger commisions (depends on the site and volume of content). I like Google best as you get paid for the click, you never lose.

I run my free business websites on this principal, bigger sites can demand much higher prices simply for display so its a differant ballpark.

Anyway, I suggest minimal use of interstitail ads, fixed position (well placed and colour matching) has always been my winner.

UPDATE - missed the SEO part sorry.

From my experience interstitail ads are only damaging to SEO if you allow full page ads to open on a visitors first page visit. Example, Adsense Full page ads can be set to be displayed to visitors after a number of page views (1,3,5 if I recall correctly). I experimented with the 1 page ads but found that:
a, my ad revenue went down (surprisingly)
b, I had less page views with much higher bounce rates (not surprisingly)
c, page integration to search engines was slower (I'm guessing that the spiders bounced too)

Notwithstanding this, there was no change to actual page rank and visitor level were pretty much the same. From this we can conclude that full page ads are not the money spinner they would initially appear to be. To be honest, I dont think I would use this as an advertising means either.

Full page ads are on a par with pamphlets through your door, at first they were shiny and interesting, after a while they just get damn annoying. Once you annoy a user, you lose their interest! the rest is obvious.

I hope this helps. Maybe someone else has had some success.