It IS quite a paranoid way of thinking about things, but when I find that most of the testimonies about NBE are accompanied with affiliate links and superlatives in their claims, something just seems too good to be true.
1. Web Based Testimonials should include the entire story, from beginning to end. This means including what has and hasn't worked for you.
2. Affiliate links degrade the integrity of a testimonial. Include no links at all, or if you absolutely feel you need to do so, include links with a rel="nofollow" attribute. If it's truly awesome, word will get around about it. But affiliate links just reduce your credibility, and for what? If you are not credible, you are of no benefit to the people you are speaking to.
3. Try to speak as objectively as possible. If you encountered some sort of snag in the process, do tell! If the customer service department of some online vendor has not acted honourably, let us know! But keep in mind to make it so that the product that has worked for you, is depicted as imperfect. Some things work for some people and some do not.
These are just my beliefs. Take them and leave them as you will.
Testamonials should be based on real experience, but if something worked for you, you should be able to direct others to that source. To some extent, this forum and others is the way the "word gets around."
If you follow a link, affiliate or otherwise, as an adult you should be able to determine its value for yourself. At my website www.male-breast-enlargement.org I review and recommend products which I have tried. Some of the products have affiliate links and some do not.
I review Transfemme and Nature's Day products, for example, which have no affiliate association. I also found Fat2Fem and Perfect Woman good products and they do have an affiliate association on my site.
I am hopeful that with my posts and with my website, the general content makes them worthwhile, irregardless of any affiliate links I might include.