About a year ago I noticed a few ClickBank products listed on AdWords. I figured they'd get slapped sooner or later but time passed and they were still there. I know the niche somewhat and the keywords that convert in that niche and sure enough - these guys have affiliates promoting straight thru AdWords PPC with no issues.
They are still there in AdWords to this very day.
A few months ago after reading the Google AdWords forums I decided to try AdWords again. And for the last few months I've been getting Display Network & Search traffic direct linking affiliate offers with no issues whatsoever :-)
One campaign is directed at my own authority site where I sell "membership". It converts well with cold traffic and on the backend I can promote more edgy stuff off of my list. It's in the meditation niche and I even have a landing page for a free ebook and videos relevant to the niche. The site has about 40pgs of content on it.
The other campaigns are pretty much all direct links to some affiliate offers (not clickbank but more exclusive affiliate networks). I love doing ClickBank stuff but I don't see many CB offers that really meet Google's editorial guidelines and the products I did stumble across are not in niches I particularly am interested in.
Now there is no point in me re-hashing all the stuff about landing page quality as Google has written so much themselves that you need to just read on your own.
I'll share with you what points I think most affiliates are missing and some links that I believe will help you understand the "Google Mindset".
1) Nothing Edgy - niches that promise to turn water into gas, help you develop mental telepathy or get six pack abs in 3 weeks are probably all going to get your account dinged. Stay away from the "make money fast" niche.
2) Testimonials - The site's testimonials are all properly caveated with "Results are not typical".
3) Transparency - The site has appropriate privacy, income disclosures, contact information. The site is easy to navigate and consumers can understand who they are buying from and exactly what they are buying.
4) Nothing Pushy - stay away from pop-ups, pop-unders, light boxes that are in your face.
5) Relevance - Your site content has to be relevant to what you're promoting. Write more content relevant to the keywords you're interested in.
I've carefully and cautiously moved some of my Bing ad campaigns back onto Google. The traffic (as we all know) is much better and the volume of traffic is awesome.
I've re-written the ad copy to be much less edgy on Google.
I've even called up AdWords and reviewed my campaigns with them telling them openly "I want to hold onto my account - these are quality offers and I think they're worth promoting". They're pretty helpful on the phone.
Some really helpful links if you want to experiment:
Webmaster Guidelines - Webmaster Tools Help
A Modern Marketing Strategy
Think with Google
ZMOT (Zero Moment of Truth) gives you a good feel for what google believes is the right way to market products. Definitely worth a read.