Note: I think the line where readers will push back probably will vary from blog to blog depending upon their readership. For example here on ProBlogger I get a little more negative feedback from readers on affiliate promotions. I suspect ProBlogger readers are a little more tuned into the issue and suspicious of some of the affiliate marketing that goes on around the web.
Once you’ve set up your account, do note that Amazon requires you to use product links and generate income from at least three of them within 180 days. If you fail to do so within that time, they will close your account. If you are able to satisfy that requirement, Amazon will review your account as well as your usage of affiliate links once the first sale is complete.