AdSense doesn't provide guidelines on using affiliate links, but it does provide guidelines on the contents you can place Adsense ads on. One of those stipulations is that your contents must be original, another involves not using unsuitable contents (such as adult contents, or contents on drugs and some types of supplements that might be illegal in the US, or gambling) ... there are too many "Prohibited Contents" to mention one-by-one here. Just make sure to read the policy.
Those policies basically mean that anything you put on your pages that have an AdSense ad on them must also comply with the policies, and that means any affiliate links should also comply. Don't use affiliate links to sites that contain contents prohibited for Adsense.
Because you need original contents, if your pages only contain a bunch of affiliate links from somewhere like Amazon, and only contain the the original reviews and summaries, don't put Adsense ads on those pages. Pages like that would fall into the "thin affiliates" category.
Don't put Adsense ads on a page whose sole purpose is to promote an affiliate - pages like that are nothing more than a gigantic advertisement for the affiliate product. If it looks like an affiliate promotion, smells like an affiliate promotion, and sounds like an affiliate promotion ... leave Adsense off of that content. Don't put adsense on e-stores with no original contents, and almost no textual contents. This would also be considered a "thin affiliate" site.
Make sure any page(s) that contain your affiliate links use the "no follow" attribute for all the links, and make sure you have more original contents of your own than affiliate links. One or two lines of text with half a dozen affiliate links is not going to be considered as:
Write an article, one that provides some useful and personal insights, then you can include an affiliate link or two with the article, along with your Adsense ads.
Learn to think like Adsense. When an AdWords advertiser puts their ad on your site ... why are they putting it there? They want people to see their product or service, they don't want it alongside a dozen other similar products owned by different companies. The chances of someone being interested enough to visit the AdWords advertiser grow smaller with each affiliate link that's on the same the page.
Keep your affiliate links on your AdSense monetized pages to a small, reasonable amount and you can have an effective page that can work for both types of advertising, and may earn you money from both.
posted by J. Gracey Stinson