A lot of surfers are wary of affiliate links, and in certain circumstances, this is fully justified. Especially if the article is meant to be a review of a product that is linked to. Ok, the author might genuinely like the product but loses credibility with an affiliate link at the end. Some affiliate sites pretend to review a product but are just a promotional sales page for the item. These sites are annoying and I hope Google finds a way of removing them from the top of the search results page. These misleading techniques are rife in the Internet Marketing products arena.
So this is one case. Affiliate links always insert a cookie into your browser which help to reward the person captured your click. This is not a problem per se but if you clicked on an article that was a content-less spun stuff that did not add any value yet later you went and bought something from the site it linked to - like Amazon - would you like the owner of that pointless article to be rewarded? Ok, you can clear your cookies if you are savvy enough but this can be a hassle, as other important site cookies might be removed to (eg. Gmail double log-in would want extra security again, your bank would want your un-memorable user number re-entered, etc.) The other situation which is, from my experience, thankfully rare is when the landing vendor site charges a higher price due to you coming through an affiliate. Vendors who do this tend to be small and unscrupulous ones who you are best to avoid anyway. Most people will Google the product of interest for price and such vendors can be uncovered and avoided..
However, some internet users are afraid of affiliate links for the "wrong" reasons. Some cite privacy concerns. This is largely an unfounded fear because affiliate links rarely track any personal details. It just passes the affiliate tracking info that will be used to credit the site you used the link from. In fact if you got value from the content of that site, it is a nice little thank you to the owner who created it. On multiple product review sites, if many affiliate links go to the different vendors, it is unlikely that the reviews are "rigged".
There are other added-value sites that help reduce time and effort to find a specific product. These can be useful to short-list your product choice and reduce the research needed. I have an Amazon electronics product site where only 4 or 5 star review items are listed where you can also limit the search by stating your price band. All links to the products are Amazon affiliate links but hey, I put in the effort to help you find the product!
So affiliate links can be a way of rewarding someone if they have in some way made your life easier or save you some time. On this site , I only have affiliate links to products I have used and approve of and judged as being of good value and quality.