I think it is a matter of balance. How much content is on a page? A few words a photo and 5 aff links? Yes you will get slapped for that.
On the other hand of you got 2000 words, 10 photos and 5 aff links "G" will not give a shit. You got balance on your page due to the content and photos. Google does have the ability to read everything on your page and rank the page based on this.
Google uses this to determine what kind of site you have. If they judge your site as thin content with lots of aff links then they don't want to send people to this site as their stats indicate a high bounce rate and dissatisfaction on the part of the search user.
i always have adsense on every site I build so google thinks they can make $$ by sending more people to my site verses some one with only aff links. i don't know for sure if this actually works but keeping in mind google is a for profit company and they will do things that are in the best interest of making $$ I trust they will continue to show me the love, just like they have ever since adsense was started and I put it on my first sites many yrs ago.
It also helps to be sure your site is indexed right away, the adsense spider does double duty as a search index spider now so use the little bugger to your advantage.
If adsense is not the focus for the site I will just ad a link unit right under the menu. This blends in well, does not get many clicks but If it is an aff site I want aff clicks.
I am big in the plant and tree affiliate area, I have tons of plant and tree related sites and I don't want my visitors clicking on adsense. The link unit is perfect for this as it does not distract my visitors from the big red buy now button with the aff link in it.
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