An affiliate marketing campaign success can depend on several factors and the most important two factors I would emphasize on are:
1. Your credibility and trust relation with your readers
2. A promising solid product to promote
The first factor again depends on several other facts like popularity of your blog, your previous recommendations and our authority in the niche. It’s very important that you refer products that you like personally and avoid chasing products that has been successful for other webmasters.
If you really want to know if you like the product, there is no other method other than thoroughly testing the product! Many product developers will be happy to share a review copy to a serious blogger reviewing such applications regularly and on the flip side if you don’t receive a review copy – I would recommend purchasing the product your self and trying. If it is really cool stuff, am sure you will recover the investment and earn multiples of that money as affiliate commissions.
It’s very obvious that readers will consider purchasing the product when they have an authoritative review from an expert who is himself ready to spend the money before recommending others to shell some cash!
Take Home: Make sure you follow the ethics of Affiliate marketing and promote products that yourselves would have purchased! Never opt for any product simply based on its market popularity.