For a long time, I was under the impression that if you had to make a choice between Google Adsense and Affiliate Banners on a webpage.

The Google Adsense program policies say:

"We do not permit Google ads or search boxes accessing Google search services to be published on web pages that also contain what could be considered competing ads or services"

But also go on to say:

"We do allow affiliate or limited-text links"

I was a little confused as a banner from an affiliate network like TradeDoubler might be considered a competing ad, but it is also an affiliate link. I'm a real stickler for playing by the rules with Google Adsense, as its such a good scheme to use, so decided to check it out.

I emailed Google Customer Support who replied and said:

"I can confirm that According to our programme policies TradeDoubler ads are not considered competing ads."

So I think when they talk about competing ads, they probably mean similar contextual text based advert services mainly.