nomis5 - 8:23 am on Sep 11, 2013 (gmt 0)
For several years I ran Adsense image ads and other image ads (from two different affiliates) on the same website and the same pages at the same time. That didn't get me into any trouble with Adsense. I then sold the website but those same image ads are still appearing and generating income both Adsense and the affiates.
Just gone back to that website now and I see one Adsense 300x250 appearing right next to an affiliate 300x250 ad and as far as I see they are almost indistinguishable except for the little triangle on the Adsense ads.
That's my mileage, based on five years or so of displaying both types of ad. But different sites are treated differently by Adsense for a huge variety of reasons so don't take this as a green light for publishing ads in that manner. It just worked OK for me and still is working for the current owner of the website.