From what I could learn, Google does all they can to show users what they are looking for. Algorithms to do that change, as some people get "clever" on how to "cheat" the ranking, without proper content. This page explains their affiliate policy:
I have used Amazon affiliate to offer recommendations to readers, usually at the end of articles dealing with a certain topic that products are used for. Didn't notice any poor ranking after introducing links.
That's what Google defines as "adding value affiliate" - people would post questions "what do you recommend to buy" before the addition of affiliate recommendations.
Best way to do a quick check whether your affiliate policy can be considered "thin", or genuine would be: "if I were reading this page for the info it provides, would I look/like to see a shopping link, or would it be logical to see one at least?"
Did however inquire, even asked a quesion here, whether to put "nofollow" on those links. Decided it's safer to do so, but not 100% certain. Will know in a month or two, having added the nofollow to all the affiliate links today.
Also beware of Amazon affiliate policies, so they don't "kick you out":
State clearly that it's an affiliate, that you're getting the percentage (without the price increase to the customer, compared to a "regular" Amazon visit).
Make sure that affiliate links are clearly marked for what they are. So people know that when they click, they will be going to Amazon shopping website.
Don't state any prices. If you insist on that, do it through Amazon's API - it will automatically check and fetch current prices and availability. Stating wrong price, item description etc. is not permitted.
Amazon says they don't like link cloaking.